less.man

LESS(1)                     General Commands Manual                    LESS(1)



NAME
       less - opposite of more

SYNOPSIS
       less -?
       less --help
       less -V
       less --version
       less [-[+]aABcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~]
            [-b space] [-h lines] [-j line] [-k keyfile]
            [-{oO} logfile] [-p pattern] [-P prompt] [-t tag]
            [-T tagsfile] [-x tab,...] [-y lines] [-[z] lines]
            [-# shift] [+[+]cmd] [--] [filename]...
       (See  the  OPTIONS section for alternate option syntax with long option
       names.)

DESCRIPTION
       Less is a program similar to more(1), but which allows  backward  move-
       ment in the file as well as forward movement.  Also, less does not have
       to read the entire input file before  starting,  so  with  large  input
       files  it  starts  up  faster  than text editors like vi(1).  Less uses
       termcap (or terminfo on some systems), so it can run on  a  variety  of
       terminals.   There is even limited support for hardcopy terminals.  (On
       a hardcopy terminal, lines which should be printed at the  top  of  the
       screen are prefixed with a caret.)

       Commands  are based on both more and vi.  Commands may be preceded by a
       decimal number, called N in the descriptions below.  The number is used
       by some commands, as indicated.

COMMANDS
       In  the following descriptions, ^X means control-X.  ESC stands for the
       ESCAPE key; for example ESC-v means the  two  character  sequence  "ES-
       CAPE", then "v".

       h or H Help:  display  a  summary of these commands.  If you forget all
              the other commands, remember this one.

       SPACE or ^V or f or ^F
              Scroll forward N lines, default one window (see  option  -z  be-
              low).  If N is more than the screen size, only the final screen-
              ful is displayed.  Warning: some systems use  ^V  as  a  special
              literalization character.

       z      Like  SPACE,  but  if  N is specified, it becomes the new window
              size.

       ESC-SPACE
              Like SPACE, but scrolls a full screenful,  even  if  it  reaches
              end-of-file in the process.

       ENTER or RETURN or ^N or e or ^E or j or ^J
              Scroll  forward N lines, default 1.  The entire N lines are dis-
              played, even if N is more than the screen size.

       d or ^D
              Scroll forward N lines, default one half of the screen size.  If
              N  is specified, it becomes the new default for subsequent d and
              u commands.

       b or ^B or ESC-v
              Scroll backward N lines, default one window (see option  -z  be-
              low).  If N is more than the screen size, only the final screen-
              ful is displayed.

       w      Like ESC-v, but if N is specified, it  becomes  the  new  window
              size.

       y or ^Y or ^P or k or ^K
              Scroll backward N lines, default 1.  The entire N lines are dis-
              played, even if N is more than the screen size.   Warning:  some
              systems use ^Y as a special job control character.

       u or ^U
              Scroll  backward  N  lines, default one half of the screen size.
              If N is specified, it becomes the new default for  subsequent  d
              and u commands.

       J      Like j, but continues to scroll beyond the end of the file.

       K or Y Like  k,  but  continues  to  scroll beyond the beginning of the
              file.

       ESC-) or RIGHTARROW
              Scroll horizontally right N characters, default half the  screen
              width  (see  the -# option).  If a number N is specified, it be-
              comes the default for future RIGHTARROW and LEFTARROW  commands.
              While  the  text  is  scrolled,  it acts as though the -S option
              (chop lines) were in effect.

       ESC-( or LEFTARROW
              Scroll horizontally left N characters, default half  the  screen
              width  (see  the -# option).  If a number N is specified, it be-
              comes the default for future RIGHTARROW and LEFTARROW commands.

       ESC-} or ^RIGHTARROW
              Scroll horizontally right to show the end of  the  longest  dis-
              played line.

       ESC-{ or ^LEFTARROW
              Scroll horizontally left back to the first column.

       r or ^R or ^L
              Repaint the screen.

       R      Repaint  the  screen,  discarding  any buffered input.  That is,
              reload the current file.  Useful if the file is  changing  while
              it is being viewed.

       F      Scroll  forward, and keep trying to read when the end of file is
              reached.  Normally this command would be used  when  already  at
              the  end of the file.  It is a way to monitor the tail of a file
              which is growing while it is being  viewed.   (The  behavior  is
              similar  to  the  "tail  -f" command.)  To stop waiting for more
              data, enter the interrupt character (usually ^C).  On some  sys-
              tems  you  can  also  use  ^X.   If  the input is a pipe and the
              --exit-follow-on-close option is in effect, less will  automati-
              cally  stop  waiting for data when the input side of the pipe is
              closed.

       ESC-F  Like F, but as soon as a line is found which  matches  the  last
              search  pattern, the terminal bell is rung and forward scrolling
              stops.

       g or < or ESC-<
              Go to line N in the file, default 1 (beginning of file).  (Warn-
              ing: this may be slow if N is large.)

       G or > or ESC->
              Go  to  line N in the file, default the end of the file.  (Warn-
              ing: this may be slow if N is large, or if N  is  not  specified
              and standard input, rather than a file, is being read.)

       ESC-G  Same  as  G, except if no number N is specified and the input is
              standard input,  goes  to  the  last  line  which  is  currently
              buffered.

       p or % Go to a position N percent into the file.  N should be between 0
              and 100, and may contain a decimal point.

       P      Go to the line containing byte offset N in the file.

       {      If a left curly bracket appears in the top line displayed on the
              screen,  the  {  command  will  go  to  the matching right curly
              bracket.  The matching right curly bracket is positioned on  the
              bottom line of the screen.  If there is more than one left curly
              bracket on the top line, a number N may be used to  specify  the
              N-th bracket on the line.

       }      If a right curly bracket appears in the bottom line displayed on
              the screen, the } command will go to  the  matching  left  curly
              bracket.   The  matching left curly bracket is positioned on the
              top line of the screen.  If there is more than one  right  curly
              bracket  on  the  bottom line, a number N may be used to specify
              the N-th bracket on the line.

       (      Like {, but applies to parentheses rather than curly brackets.

       )      Like }, but applies to parentheses rather than curly brackets.

       [      Like {, but applies to square brackets rather than curly  brack-
              ets.

       ]      Like  }, but applies to square brackets rather than curly brack-
              ets.

       ESC-^F Followed by two characters, acts like {, but uses the two  char-
              acters  as  open and close brackets, respectively.  For example,
              "ESC ^F < >" could be used to go forward to the > which  matches
              the < in the top displayed line.

       ESC-^B Followed  by two characters, acts like }, but uses the two char-
              acters as open and close brackets, respectively.   For  example,
              "ESC ^B < >" could be used to go backward to the < which matches
              the > in the bottom displayed line.

       m      Followed by any lowercase or uppercase letter, marks  the  first
              displayed  line  with  that letter.  If the status column is en-
              abled via the -J option, the  status  column  shows  the  marked
              line.

       M      Acts  like  m,  except  the last displayed line is marked rather
              than the first displayed line.

       '      (Single quote.)  Followed by any lowercase or uppercase  letter,
              returns  to  the  position which was previously marked with that
              letter.  Followed by another single quote, returns to the  posi-
              tion  at  which  the last "large" movement command was executed.
              Followed by a ^ or $, jumps to the beginning or end of the  file
              respectively.   Marks are preserved when a new file is examined,
              so the ' command can be used to switch between input files.

       ^X^X   Same as single quote.

       ESC-m  Followed by any lowercase or uppercase letter, clears  the  mark
              identified by that letter.

       /pattern
              Search forward in the file for the N-th line containing the pat-
              tern.  N defaults to 1.  The pattern is a regular expression, as
              recognized  by  the  regular expression library supplied by your
              system.  The search starts at the first line displayed (but  see
              the -a and -j options, which change this).

              Certain  characters  are  special if entered at the beginning of
              the pattern; they modify the type of search rather  than  become
              part of the pattern:

              ^N or !
                     Search for lines which do NOT match the pattern.

              ^E or *
                     Search  multiple  files.   That is, if the search reaches
                     the END of the current file without finding a match,  the
                     search  continues  in  the  next file in the command line
                     list.

              ^F or @
                     Begin the search at the first line of the FIRST  file  in
                     the  command  line  list, regardless of what is currently
                     displayed on the screen or the settings of the -a  or  -j
                     options.

              ^K     Highlight  any text which matches the pattern on the cur-
                     rent screen, but don't move to the first match (KEEP cur-
                     rent position).

              ^R     Don't  interpret  regular expression metacharacters; that
                     is, do a simple textual comparison.

              ^W     WRAP around the current file.  That  is,  if  the  search
                     reaches  the  end  of  the current file without finding a
                     match, the search continues from the first  line  of  the
                     current  file up to the line where it started.  If the ^W
                     modifier is set, the ^E modifier is ignored.

       ?pattern
              Search backward in the file for the  N-th  line  containing  the
              pattern.   The search starts at the last line displayed (but see
              the -a and -j options, which change this).

              Certain characters are special as in the / command:

              ^N or !
                     Search for lines which do NOT match the pattern.

              ^E or *
                     Search multiple files.  That is, if  the  search  reaches
                     the  beginning  of  the  current  file  without finding a
                     match, the search continues in the previous file  in  the
                     command line list.

              ^F or @
                     Begin the search at the last line of the last file in the
                     command line list, regardless of what is  currently  dis-
                     played  on the screen or the settings of the -a or -j op-
                     tions.

              ^K     As in forward searches.

              ^R     As in forward searches.

              ^W     WRAP around the current file.  That  is,  if  the  search
                     reaches the beginning of the current file without finding
                     a match, the search continues from the last line  of  the
                     current file up to the line where it started.

       ESC-/pattern
              Same as "/*".

       ESC-?pattern
              Same as "?*".

       n      Repeat  previous  search, for N-th line containing the last pat-
              tern.  If the previous search was modified by ^N, the search  is
              made  for the N-th line NOT containing the pattern.  If the pre-
              vious search was modified by ^E, the  search  continues  in  the
              next  (or  previous)  file if not satisfied in the current file.
              If the previous search was modified by ^R, the  search  is  done
              without  using  regular  expressions.  There is no effect if the
              previous search was modified by ^F or ^K.

       N      Repeat previous search, but in the reverse direction.

       ESC-n  Repeat previous search, but crossing file boundaries.   The  ef-
              fect is as if the previous search were modified by *.

       ESC-N  Repeat  previous search, but in the reverse direction and cross-
              ing file boundaries.

       ESC-u  Undo search highlighting.   Turn  off  highlighting  of  strings
              matching the current search pattern.  If highlighting is already
              off because of a previous ESC-u command, turn highlighting  back
              on.   Any  search  command  will also turn highlighting back on.
              (Highlighting can also be disabled by toggling the -G option; in
              that case search commands do not turn highlighting back on.)

       ESC-U  Like  ESC-u  but  also  clears the saved search pattern.  If the
              status column is enabled via the  -J  option,  this  clears  all
              search matches marked in the status column.

       &pattern
              Display  only  lines which match the pattern; lines which do not
              match the pattern are not displayed.  If pattern  is  empty  (if
              you  type  &  immediately  followed  by ENTER), any filtering is
              turned off, and all lines are displayed.  While filtering is  in
              effect,  an  ampersand  is  displayed  at  the  beginning of the
              prompt, as a reminder that some lines in the file may be hidden.
              Multiple  &  commands  may  be entered, in which case only lines
              which match all of the patterns will be displayed.

              Certain characters are special as in the / command:

              ^N or !
                     Display only lines which do NOT match the pattern.

              ^R     Don't interpret regular expression  metacharacters;  that
                     is, do a simple textual comparison.

       :e [filename]
              Examine  a  new file.  If the filename is missing, the "current"
              file (see the :n and :p commands below) from the list  of  files
              in  the  command line is re-examined.  A percent sign (%) in the
              filename is replaced by the name of the current file.   A  pound
              sign  (#)  is  replaced  by  the name of the previously examined
              file.  However, two consecutive percent  signs  are  simply  re-
              placed  with  a single percent sign.  This allows you to enter a
              filename that contains a percent sign in the  name.   Similarly,
              two  consecutive  pound  signs  are replaced with a single pound
              sign.  The filename is inserted into the command  line  list  of
              files  so  that it can be seen by subsequent :n and :p commands.
              If the filename consists of several files, they are all inserted
              into  the  list  of files and the first one is examined.  If the
              filename contains one or more spaces, the entire filename should
              be enclosed in double quotes (also see the -" option).

       ^X^V or E
              Same  as :e.  Warning: some systems use ^V as a special literal-
              ization character.  On such systems, you may not be able to  use
              ^V.

       :n     Examine  the next file (from the list of files given in the com-
              mand line).  If a number N is specified, the N-th next  file  is
              examined.

       :p     Examine the previous file in the command line list.  If a number
              N is specified, the N-th previous file is examined.

       :x     Examine the first file in the command line list.  If a number  N
              is specified, the N-th file in the list is examined.

       :d     Remove the current file from the list of files.

       t      Go  to the next tag, if there were more than one matches for the
              current tag.  See the -t option for more details about tags.

       T      Go to the previous tag, if there were more than one matches  for
              the current tag.

       = or ^G or :f
              Prints  some  information about the file being viewed, including
              its name and the line number and byte offset of the bottom  line
              being  displayed.  If possible, it also prints the length of the
              file, the number of lines in the file and  the  percent  of  the
              file above the last displayed line.

       -      Followed  by one of the command line option letters (see OPTIONS
              below), this will change the setting of that option and print  a
              message  describing the new setting.  If a ^P (CONTROL-P) is en-
              tered immediately after the dash, the setting of the  option  is
              changed  but  no message is printed.  If the option letter has a
              numeric value (such as -b or -h), or a string value (such as  -P
              or  -t), a new value may be entered after the option letter.  If
              no new value is entered, a message describing the  current  set-
              ting is printed and nothing is changed.

       --     Like  the  -  command, but takes a long option name (see OPTIONS
              below) rather than a single option letter.  You must press ENTER
              or  RETURN after typing the option name.  A ^P immediately after
              the second dash suppresses printing of a message describing  the
              new setting, as in the - command.

       -+     Followed by one of the command line option letters this will re-
              set the option to its default setting and print  a  message  de-
              scribing  the  new  setting.   (The  "-+X" command does the same
              thing as "-+X" on the command line.)  This  does  not  work  for
              string-valued options.

       --+    Like  the -+ command, but takes a long option name rather than a
              single option letter.

       -!     Followed by one of the command line option  letters,  this  will
              reset  the  option  to the "opposite" of its default setting and
              print a message describing the new setting.  This does not  work
              for numeric or string-valued options.

       --!    Like  the -! command, but takes a long option name rather than a
              single option letter.

       _      (Underscore.)  Followed by one of the command line  option  let-
              ters,  this  will print a message describing the current setting
              of that option.  The setting of the option is not changed.

       __     (Double underscore.)  Like the _ (underscore) command, but takes
              a long option name rather than a single option letter.  You must
              press ENTER or RETURN after typing the option name.

       +cmd   Causes the specified cmd to be executed each time a new file  is
              examined.  For example, +G causes less to initially display each
              file starting at the end rather than the beginning.

       V      Prints the version number of less being run.

       q or Q or :q or :Q or ZZ
              Exits less.

       The following four commands may or may not be valid, depending on  your
       particular installation.

       v      Invokes  an  editor  to edit the current file being viewed.  The
              editor is taken from the environment variable VISUAL if defined,
              or  EDITOR if VISUAL is not defined, or defaults to "vi" if nei-
              ther VISUAL nor EDITOR is defined.  See also the  discussion  of
              LESSEDIT under the section on PROMPTS below.

       ! shell-command
              Invokes  a shell to run the shell-command given.  A percent sign
              (%) in the command is replaced by the name of the current  file.
              A pound sign (#) is replaced by the name of the previously exam-
              ined file.  "!!" repeats the last shell command.   "!"  with  no
              shell  command  simply  invokes  a  shell.  On Unix systems, the
              shell is taken from the environment variable SHELL, or  defaults
              to  "sh".   On  MS-DOS and OS/2 systems, the shell is the normal
              command processor.

       | <m> shell-command
              <m> represents any mark letter.  Pipes a section  of  the  input
              file  to the given shell command.  The section of the file to be
              piped is between the position marked by the letter and the  cur-
              rent  screen.  The entire current screen is included, regardless
              of whether the marked position is before or  after  the  current
              screen.   <m> may also be ^ or $ to indicate beginning or end of
              file respectively.  If <m> is . or newline, the  current  screen
              is piped.

       s filename
              Save  the  input  to  a file.  This only works if the input is a
              pipe, not an ordinary file.

OPTIONS
       Command line options are described below.  Most options may be  changed
       while less is running, via the "-" command.

       Most  options  may be given in one of two forms: either a dash followed
       by a single letter, or two dashes followed by a long  option  name.   A
       long  option name may be abbreviated as long as the abbreviation is un-
       ambiguous.  For example, --quit-at-eof may be abbreviated  --quit,  but
       not --qui, since both --quit-at-eof and --quiet begin with --qui.  Some
       long option names are in uppercase, such as --QUIT-AT-EOF, as  distinct
       from  --quit-at-eof.  Such option names need only have their first let-
       ter capitalized; the remainder of the name may be in either case.   For
       example, --Quit-at-eof is equivalent to --QUIT-AT-EOF.

       Options are also taken from the environment variable "LESS".  For exam-
       ple, to avoid typing "less -options ..." each time less is invoked, you
       might tell csh:

       setenv LESS "-options"

       or if you use sh:

       LESS="-options"; export LESS

       On  MS-DOS,  you don't need the quotes, but you should replace any per-
       cent signs in the options string by double percent signs.

       The environment variable is parsed before the command line, so  command
       line  options override the LESS environment variable.  If an option ap-
       pears in the LESS variable, it can be reset to its default value on the
       command line by beginning the command line option with "-+".

       Some  options  like -k or -D require a string to follow the option let-
       ter.  The string for that option is considered to  end  when  a  dollar
       sign  ($)  is found.  For example, you can set two -D options on MS-DOS
       like this:

       LESS="Dn9.1$Ds4.1"

       If the --use-backslash option appears earlier in the  options,  then  a
       dollar  sign or backslash may be included literally in an option string
       by preceding it with a backslash.  If the --use-backslash option is not
       in  effect, then backslashes are not treated specially, and there is no
       way to include a dollar sign in the option string.

       -? or --help
              This option displays a summary of the commands accepted by  less
              (the  same  as the h command).  (Depending on how your shell in-
              terprets the question mark, it may be  necessary  to  quote  the
              question mark, thus: "-\?".)

       -a or --search-skip-screen
              By  default,  forward searches start at the top of the displayed
              screen and backwards searches start at the bottom  of  the  dis-
              played  screen (except for repeated searches invoked by the n or
              N commands, which start after or before the  "target"  line  re-
              spectively;  see  the -j option for more about the target line).
              The -a option causes forward searches to instead  start  at  the
              bottom  of  the screen and backward searches to start at the top
              of the screen, thus skipping all lines displayed on the screen.

       -A or --SEARCH-SKIP-SCREEN
              Causes all forward searches (not just non-repeated searches)  to
              start  just  after the target line, and all backward searches to
              start just before the target line.  Thus, forward searches  will
              skip part of the displayed screen (from the first line up to and
              including the target line).  Similarly backwards  searches  will
              skip the displayed screen from the last line up to and including
              the target line.  This was the default behavior in less versions
              prior to 441.

       -bn or --buffers=n
              Specifies  the  amount  of  buffer  space less will use for each
              file, in units of kilobytes (1024 bytes).  By default  64 KB  of
              buffer  space  is used for each file (unless the file is a pipe;
              see the -B option).  The -b  option  specifies  instead  that  n
              kilobytes of buffer space should be used for each file.  If n is
              -1, buffer space is unlimited; that is, the entire file  can  be
              read into memory.

       -B or --auto-buffers
              By default, when data is read from a pipe, buffers are allocated
              automatically as needed.  If a large amount of data is read from
              the  pipe,  this  can cause a large amount of memory to be allo-
              cated.  The -B option disables this automatic allocation of buf-
              fers for pipes, so that only 64 KB (or the amount of space spec-
              ified by the -b option) is used for the pipe.  Warning:  use  of
              -B can result in erroneous display, since only the most recently
              viewed part of the piped data is kept  in  memory;  any  earlier
              data is lost.

       -c or --clear-screen
              Causes  full  screen  repaints  to  be painted from the top line
              down.  By default, full screen repaints are  done  by  scrolling
              from the bottom of the screen.

       -C or --CLEAR-SCREEN
              Same as -c, for compatibility with older versions of less.

       -d or --dumb
              The -d option suppresses the error message normally displayed if
              the terminal is dumb; that is, lacks some important  capability,
              such as the ability to clear the screen or scroll backward.  The
              -d option does not otherwise change the behavior of  less  on  a
              dumb terminal.

       -Dxcolor or --color=xcolor
              Changes  the  color of different parts of the displayed text.  x
              is a single character which selects the type of text whose color
              is being set:

              B      Binary characters.

              C      Control characters.

              E      Errors and informational messages.

              H      Header lines and columns, set via the --header option.

              M      Mark letters in the status column.

              N      Line numbers enabled via the -N option.

              P      Prompts.

              R      The rscroll character.

              S      Search results.

              W      The highlight enabled via the -w option.

              d      Bold text.

              k      Blinking text.

              s      Standout text.

              u      Underlined text.

              The  uppercase letters can be used only when the --use-color op-
              tion is enabled.  When text color is specified by both an upper-
              case  letter  and a lowercase letter, the uppercase letter takes
              precedence.  For example, error messages are normally  displayed
              as standout text.  So if both "s" and "E" are given a color, the
              "E" color applies to error messages, and the "s"  color  applies
              to  other  standout text.  The "d" and "u" letters refer to bold
              and underline text formed by overstriking with  backspaces  (see
              the -u option), not to text using ANSI escape sequences with the
              -R option.

              A lowercase letter may be followed by a + to indicate  that  the
              normal  format  change  and  the  specified color should both be
              used.  For example, -Dug displays underlined text as green with-
              out  underlining;  the green color has replaced the usual under-
              line formatting.  But -Du+g displays  underlined  text  as  both
              green and in underlined format.

              color is either a 4-bit color string or an 8-bit color string:

              A  4-bit  color string is zero, one or two characters, where the
              first character specifies the foreground color  and  the  second
              specifies the background color as follows:

              b      Blue

              c      Cyan

              g      Green

              k      Black

              m      Magenta

              r      Red

              w      White

              y      Yellow

              The  corresponding upper-case letter denotes a brighter shade of
              the color.  For example, -DNGk displays line numbers  as  bright
              green  text on a black background, and -DEbR displays error mes-
              sages as blue text on a bright red background.  If either  char-
              acter  is a "-" or is omitted, the corresponding color is set to
              that of normal text.

              An 8-bit color string is one or two decimal  integers  separated
              by a dot, where the first integer specifies the foreground color
              and the second specifies the background color.  Each integer  is
              a  value  between 0 and 255 inclusive which selects a "CSI 38;5"
              color value (see
              https://en.wikipedia.org/wiki/ANSI_escape_code#SGR)  If   either
              integer  is  a "-" or is omitted, the corresponding color is set
              to that of normal text.  On MS-DOS versions of less, 8-bit color
              is  not  supported;  instead,  decimal values are interpreted as
              4-bit CHAR_INFO.Attributes values (see
              https://docs.microsoft.com/en-us/windows/console/char-info-str).

       -e or --quit-at-eof
              Causes less to automatically exit the  second  time  it  reaches
              end-of-file.   By  default, the only way to exit less is via the
              "q" command.

       -E or --QUIT-AT-EOF
              Causes less to automatically exit the first time it reaches end-
              of-file.

       -f or --force
              Forces non-regular files to be opened.  (A non-regular file is a
              directory or a device special file.)  Also suppresses the  warn-
              ing message when a binary file is opened.  By default, less will
              refuse to open non-regular files.  Note that some operating sys-
              tems will not allow directories to be read, even if -f is set.

       -F or --quit-if-one-screen
              Causes less to automatically exit if the entire file can be dis-
              played on the first screen.

       -g or --hilite-search
              Normally, less will highlight ALL strings which match  the  last
              search  command.   The  -g option changes this behavior to high-
              light only the particular string which was  found  by  the  last
              search command.  This can cause less to run somewhat faster than
              the default.

       -G or --HILITE-SEARCH
              The -G option suppresses all highlighting of  strings  found  by
              search commands.

       -hn or --max-back-scroll=n
              Specifies  a  maximum number of lines to scroll backward.  If it
              is necessary to scroll backward more than n lines, the screen is
              repainted in a forward direction instead.  (If the terminal does
              not have the ability to scroll backward, -h0 is implied.)

       -i or --ignore-case
              Causes searches to ignore case; that is, uppercase and lowercase
              are  considered identical.  This option is ignored if any upper-
              case letters appear in the search pattern; in other words, if  a
              pattern  contains  uppercase  letters, then that search does not
              ignore case.

       -I or --IGNORE-CASE
              Like -i, but searches ignore case even if the  pattern  contains
              uppercase letters.

       -jn or --jump-target=n
              Specifies  a line on the screen where the "target" line is to be
              positioned.  The target line is the line specified by  any  com-
              mand  to  search for a pattern, jump to a line number, jump to a
              file percentage or jump to a tag.  The screen line may be speci-
              fied  by  a number: the top line on the screen is 1, the next is
              2, and so on.  The number may be negative to specify a line rel-
              ative to the bottom of the screen: the bottom line on the screen
              is -1, the second to the bottom is -2, and so on.   Alternately,
              the  screen line may be specified as a fraction of the height of
              the screen, starting with a decimal point: .5 is in  the  middle
              of  the screen, .3 is three tenths down from the first line, and
              so on.  If the line is specified as a fraction, the actual  line
              number  is  recalculated  if  the terminal window is resized, so
              that the target line remains at the specified  fraction  of  the
              screen  height.   If any form of the -j option is used, repeated
              forward searches (invoked with "n" or "N") begin at the line im-
              mediately  after the target line, and repeated backward searches
              begin at the target line, unless changed by -a or -A.  For exam-
              ple, if "-j4" is used, the target line is the fourth line on the
              screen, so forward searches begin  at  the  fifth  line  on  the
              screen.   However nonrepeated searches (invoked with "/" or "?")
              always begin at the start or end of the current  screen  respec-
              tively.

       -J or --status-column
              Displays  a  status  column at the left edge of the screen.  The
              status column shows the lines that matched the  current  search,
              and any lines that are marked (via the m or M command).

       -kfilename or --lesskey-file=filename
              Causes less to open and interpret the named file as a lesskey(1)
              binary file.  Multiple -k options  may  be  specified.   If  the
              LESSKEY  or  LESSKEY_SYSTEM environment variable is set, or if a
              lesskey file is found in a standard place (see KEY BINDINGS), it
              is also used as a lesskey file.

       --lesskey-src=filename
              Causes less to open and interpret the named file as a lesskey(1)
              source file.  If the LESSKEYIN or  LESSKEYIN_SYSTEM  environment
              variable is set, or if a lesskey source file is found in a stan-
              dard place (see KEY BINDINGS), it is  also  used  as  a  lesskey
              source  file.   Prior to version 582, the lesskey program needed
              to be run to convert a lesskey source file to a  lesskey  binary
              file  for  less to use.  Newer versions of less read the lesskey
              source file directly and ignore the binary file  if  the  source
              file exists.

       -K or --quit-on-intr
              Causes  less  to exit immediately (with status 2) when an inter-
              rupt character (usually ^C) is typed.   Normally,  an  interrupt
              character causes less to stop whatever it is doing and return to
              its command prompt.  Note that use of this option makes  it  im-
              possible to return to the command prompt from the "F" command.

       -L or --no-lessopen
              Ignore  the  LESSOPEN  environment  variable (see the INPUT PRE-
              PROCESSOR section below).  This option can be  set  from  within
              less,  but  it will apply only to files opened subsequently, not
              to the file which is currently open.

       -m or --long-prompt
              Causes less to prompt verbosely (like more),  with  the  percent
              into the file.  By default, less prompts with a colon.

       -M or --LONG-PROMPT
              Causes less to prompt even more verbosely than more.

       -n or --line-numbers
              Suppresses  line numbers.  The default (to use line numbers) may
              cause less to run more slowly in some cases, especially  with  a
              very large input file.  Suppressing line numbers with the -n op-
              tion will avoid this problem.  Using  line  numbers  means:  the
              line number will be displayed in the verbose prompt and in the =
              command, and the v command will pass the current line number  to
              the  editor  (see also the discussion of LESSEDIT in PROMPTS be-
              low).

       -N or --LINE-NUMBERS
              Causes a line number to be displayed at the  beginning  of  each
              line in the display.

       -ofilename or --log-file=filename
              Causes  less  to copy its input to the named file as it is being
              viewed.  This applies only when the input file is a pipe, not an
              ordinary  file.   If  the file already exists, less will ask for
              confirmation before overwriting it.

       -Ofilename or --LOG-FILE=filename
              The -O option is like -o, but it will overwrite an existing file
              without asking for confirmation.

              If  no log file has been specified, the -o and -O options can be
              used from within less to specify a log  file.   Without  a  file
              name, they will simply report the name of the log file.  The "s"
              command is equivalent to specifying -o from within less.

       -ppattern or --pattern=pattern
              The -p option on the command line is  equivalent  to  specifying
              +/pattern;  that  is, it tells less to start at the first occur-
              rence of pattern in the file.

       -Pprompt or --prompt=prompt
              Provides a way to tailor the three prompt  styles  to  your  own
              preference.  This option would normally be put in the LESS envi-
              ronment variable, rather than being typed in with each less com-
              mand.  Such an option must either be the last option in the LESS
              variable, or be terminated by a dollar sign.
               -Ps followed by a string changes the default (short) prompt  to
              that string.
               -Pm changes the medium (-m) prompt.
               -PM changes the long (-M) prompt.
               -Ph changes the prompt for the help screen.
               -P= changes the message printed by the = command.
               -Pw  changes the message printed while waiting for data (in the
              "F" command).

              All prompt strings consist of a sequence of letters and  special
              escape sequences.  See the section on PROMPTS for more details.

       -q or --quiet or --silent
              Causes  moderately  "quiet"  operation: the terminal bell is not
              rung if an attempt is made to scroll past the end of the file or
              before the beginning of the file.  If the terminal has a "visual
              bell", it is used instead.  The bell will  be  rung  on  certain
              other  errors, such as typing an invalid character.  The default
              is to ring the terminal bell in all such cases.

       -Q or --QUIET or --SILENT
              Causes totally "quiet" operation: the  terminal  bell  is  never
              rung.   If  the  terminal has a "visual bell", it is used in all
              cases where the terminal bell would have been rung.

       -r or --raw-control-chars
              Causes "raw" control characters to be displayed.  The default is
              to  display control characters using the caret notation; for ex-
              ample, a control-A (octal 001) is displayed as  "^A".   Warning:
              when the -r option is used, less cannot keep track of the actual
              appearance of the screen (since this depends on how  the  screen
              responds to each type of control character).  Thus, various dis-
              play problems may result, such as long lines being split in  the
              wrong place.

              USE OF THE -r OPTION IS NOT RECOMMENDED.

       -R or --RAW-CONTROL-CHARS
              Like -r, but only ANSI "color" escape sequences and OSC 8 hyper-
              link sequences are output in "raw" form.  Unlike -r, the  screen
              appearance  is  maintained correctly, provided that there are no
              escape sequences in the file other than these  types  of  escape
              sequences.   Color  escape sequences are only supported when the
              color is changed within one line, not across  lines.   In  other
              words,  the beginning of each line is assumed to be normal (non-
              colored), regardless of any escape sequences in previous  lines.
              For the purpose of keeping track of screen appearance, these es-
              cape sequences are assumed to not move the cursor.

              OSC 8 hyperlinks are sequences of the form:

                   ESC ] 8 ; ... \7

              The terminating sequence may be either a BEL character  (\7)  or
              the two-character sequence "ESC \".

              ANSI color escape sequences are sequences of the form:

                   ESC [ ... m

              where  the "..." is zero or more color specification characters.
              You can make less think that characters other than "m"  can  end
              ANSI  color escape sequences by setting the environment variable
              LESSANSIENDCHARS to the list of characters which can end a color
              escape  sequence.   And  you can make less think that characters
              other than the standard ones may appear between the ESC and  the
              m  by  setting  the environment variable LESSANSIMIDCHARS to the
              list of characters which can appear.

       -s or --squeeze-blank-lines
              Causes consecutive blank lines to  be  squeezed  into  a  single
              blank line.  This is useful when viewing nroff output.

       -S or --chop-long-lines
              Causes  lines  longer than the screen width to be chopped (trun-
              cated) rather than wrapped.  That is, the portion of a long line
              that does not fit in the screen width is not displayed until you
              press RIGHT-ARROW.  The default is to wrap long lines; that  is,
              display the remainder on the next line.

       -ttag or --tag=tag
              The -t option, followed immediately by a TAG, will edit the file
              containing that tag.  For this to work, tag information must  be
              available;  for  example, there may be a file in the current di-
              rectory called "tags", which was previously built by ctags(1) or
              an equivalent command.  If the environment variable LESSGLOBALT-
              AGS is set, it is taken to be the name of a  command  compatible
              with  global(1),  and  that command is executed to find the tag.
              (See  http://www.gnu.org/software/global/global.html).   The  -t
              option  may also be specified from within less (using the - com-
              mand) as a way of examining a new file.   The  command  ":t"  is
              equivalent to specifying -t from within less.

       -Ttagsfile or --tag-file=tagsfile
              Specifies a tags file to be used instead of "tags".

       -u or --underline-special
              Causes  backspaces  and carriage returns to be treated as print-
              able characters; that is, they are sent  to  the  terminal  when
              they appear in the input.

       -U or --UNDERLINE-SPECIAL
              Causes  backspaces, tabs, carriage returns and "formatting char-
              acters" (as defined by Unicode) to be treated as control charac-
              ters; that is, they are handled as specified by the -r option.

              By  default, if neither -u nor -U is given, backspaces which ap-
              pear adjacent to an underscore character are treated  specially:
              the  underlined  text is displayed using the terminal's hardware
              underlining capability.  Also, backspaces which  appear  between
              two  identical  characters are treated specially: the overstruck
              text is printed using the terminal's hardware boldface capabili-
              ty.   Other  backspaces  are  deleted,  along with the preceding
              character.  Carriage returns immediately followed by  a  newline
              are deleted.  Other carriage returns are handled as specified by
              the -r option.  Unicode formatting characters, such as the  Byte
              Order  Mark, are sent to the terminal.  Text which is overstruck
              or underlined can be searched for if neither -u nor -U is in ef-
              fect.

       -V or --version
              Displays the version number of less.

       -w or --hilite-unread
              Temporarily  highlights  the  first  "new"  line after a forward
              movement of a full page.  The first "new" line is the line imme-
              diately  following  the  line  previously  at  the bottom of the
              screen.  Also highlights the target line after a g or p command.
              The  highlight is removed at the next command which causes move-
              ment.  If the --status-line option is in effect, the entire line
              (the  width  of the screen) is highlighted.  Otherwise, only the
              text in the line is highlighted, unless the -J option is in  ef-
              fect, in which case only the status column is highlighted.

       -W or --HILITE-UNREAD
              Like -w, but temporarily highlights the first new line after any
              forward movement command larger than one line.

       -xn,... or --tabs=n,...
              Sets tab stops.  If only one n is specified, tab stops  are  set
              at  multiples  of n.  If multiple values separated by commas are
              specified, tab stops are set at those positions, and  then  con-
              tinue  with  the  same  spacing  as  the last two.  For example,
              -x9,17 will set tabs at positions 9, 17, 25, 33, etc.   The  de-
              fault for n is 8.

       -X or --no-init
              Disables sending the termcap initialization and deinitialization
              strings to the terminal.  This is  sometimes  desirable  if  the
              deinitialization  string does something unnecessary, like clear-
              ing the screen.

       -yn or --max-forw-scroll=n
              Specifies a maximum number of lines to scroll forward.  If it is
              necessary to scroll forward more than n lines, the screen is re-
              painted instead.  The -c or -C option may  be  used  to  repaint
              from  the top of the screen if desired.  By default, any forward
              movement causes scrolling.

       -zn or --window=n or -n
              Changes the default scrolling window size to n lines.   The  de-
              fault  is  one screenful.  The z and w commands can also be used
              to change the window size.  The "z" may be omitted for  compati-
              bility with some versions of more.  If the number n is negative,
              it indicates n lines less than the current screen size.  For ex-
              ample, if the screen is 24 lines, -z-4 sets the scrolling window
              to 20 lines.   If  the  screen  is  resized  to  40  lines,  the
              scrolling window automatically changes to 36 lines.

       -"cc or --quotes=cc
              Changes  the  filename quoting character.  This may be necessary
              if you are trying to name a file which contains both spaces  and
              quote  characters.  Followed by a single character, this changes
              the quote character to that character.  Filenames  containing  a
              space should then be surrounded by that character rather than by
              double quotes.  Followed by two  characters,  changes  the  open
              quote  to the first character, and the close quote to the second
              character.  Filenames containing a space should then be preceded
              by  the  open  quote  character  and followed by the close quote
              character.  Note  that  even  after  the  quote  characters  are
              changed,  this  option  remains  -" (a dash followed by a double
              quote).

       -~ or --tilde
              Normally lines after end of file are displayed as a single tilde
              (~).  This option causes lines after end of file to be displayed
              as blank lines.

       -# or --shift
              Specifies the default number of positions to scroll horizontally
              in  the RIGHTARROW and LEFTARROW commands.  If the number speci-
              fied is zero, it sets the default number  of  positions  to  one
              half of the screen width.  Alternately, the number may be speci-
              fied as a fraction of the width of the screen, starting  with  a
              decimal  point:  .5  is  half  of  the screen width, .3 is three
              tenths of the screen width, and so on.  If the number is  speci-
              fied as a fraction, the actual number of scroll positions is re-
              calculated if the terminal window is resized, so that the actual
              scroll remains at the specified fraction of the screen width.

       --exit-follow-on-close
              When  using  the  "F" command on a pipe, less will automatically
              stop waiting for more data when the input side of  the  pipe  is
              closed.

       --file-size
              If --file-size is specified, less will determine the size of the
              file immediately after opening the file.  Normally this  is  not
              done,  because  it can be slow if the input file is non-seekable
              (such as a pipe) and is large.

       --follow-name
              Normally, if the input file is renamed while an F command is ex-
              ecuting, less will continue to display the contents of the orig-
              inal file despite its name change.  If --follow-name  is  speci-
              fied,  during an F command less will periodically attempt to re-
              open the file by name.  If the reopen succeeds and the file is a
              different  file  from  the original (which means that a new file
              has been created with the same name as  the  original  (now  re-
              named) file), less will display the contents of that new file.

       --header
              Sets  the  number  of  header lines and columns displayed on the
              screen.  The value may be of the form "N,M" where N  and  M  are
              integers, to set the header lines to N and the header columns to
              M, or it may be a single integer "N" which sets the header lines
              to  N  and  the  header columns to zero.  When N is nonzero, the
              first N lines at the top of the screen  are  replaced  with  the
              first  N  lines of the file, regardless of what part of the file
              are being viewed.  When M is nonzero, the  characters  displayed
              at  the  beginning  of  each  line are replaced with the first M
              characters of the line, even if the rest of the line is scrolled
              horizontally.   If  either N or M is zero, less stops displaying
              header lines or columns, respectively.  (Note  that  it  may  be
              necessary  to change the setting of the -j option to ensure that
              the target line is not obscured by the header line(s).)

       --incsearch
              Subsequent search commands will be "incremental"; that is,  less
              will  advance  to the next line containing the search pattern as
              each character of the pattern is typed in.

       --line-num-width
              Sets the minimum width of the line number field when the -N  op-
              tion is in effect.  The default is 7 characters.

       --mouse
              Enables  mouse  input: scrolling the mouse wheel down moves for-
              ward in the file, scrolling the mouse wheel up  moves  backwards
              in  the  file,  and  clicking the mouse sets the "#" mark to the
              line where the mouse is clicked.  The number of lines to  scroll
              when  the wheel is moved can be set by the --wheel-lines option.
              Mouse input works only on terminals which support X11 mouse  re-
              porting, and on the Windows version of less.

       --MOUSE
              Like --mouse, except the direction scrolled on mouse wheel move-
              ment is reversed.

       --no-keypad
              Disables sending the keypad initialization and  deinitialization
              strings to the terminal.  This is sometimes useful if the keypad
              strings make the numeric keypad behave in an undesirable manner.

       --no-histdups
              This option changes the behavior so that if a search  string  or
              file  name  is  typed  in, and the same string is already in the
              history list, the existing copy is removed from the history list
              before  the  new one is added.  Thus, a given string will appear
              only once in the history list.  Normally, a  string  may  appear
              multiple times.

       --no-number-headers
              Header  lines (defined via the --header option) are not assigned
              line numbers.  Line number 1 is assigned to the first line after
              any header lines.

       --rscroll
              This  option changes the character used to mark truncated lines.
              It may begin with a two-character attribute indicator like LESS-
              BINFMT  does.   If  there is no attribute indicator, standout is
              used.  If set to "-", truncated lines are not marked.

       --redraw-on-quit
              When  quitting,  after  sending  the  terminal  deinitialization
              string, redraws the entire last screen.  On terminals whose ter-
              minal deinitialization string causes the terminal to switch from
              an  alternate  screen, this makes the last screenful of the cur-
              rent file remain visible after less has quit.

       --save-marks
              Save marks in the history file, so  marks  are  retained  across
              different invocations of less.

       --search-options
              Sets  default search modifiers.  The value is a string of one or
              more of the characters E, F, K, N, R or W.  Setting any of these
              has  the same effect as typing that control character at the be-
              ginning of every search pattern.  For example, setting --search-
              options=W  is  the  same  as typing ^W at the beginning of every
              pattern.  The value "-" disables all default search modifiers.

       --status-col-width
              Sets the width of the status column when the -J option is in ef-
              fect.  The default is 2 characters.

       --status-line
              If  a line is marked, the entire line (rather than just the sta-
              tus column) is highlighted.  Also lines highlighted due  to  the
              -w option will have the entire line highlighted.  If --use-color
              is set, the line is colored rather than highlighted.

       --use-backslash
              This option changes the interpretations of options which  follow
              this one.  After the --use-backslash option, any backslash in an
              option string is removed and the following  character  is  taken
              literally.   This  allows a dollar sign to be included in option
              strings.

       --use-color
              Enables colored text in various places.  The -D  option  can  be
              used  to change the colors.  Colored text works only if the ter-
              minal supports ANSI color escape sequences (as  defined  in  EC-
              MA-48 SGR; see
              https://www.ecma-international.org/publications-and-
              standards/standards/ecma-48).

       --wheel-lines=n
              Set the number of lines  to  scroll  when  the  mouse  wheel  is
              scrolled  and  the  --mouse or --MOUSE option is in effect.  The
              default is 1 line.

       --     A command line argument of "--" marks the end  of  option  argu-
              ments.   Any  arguments  following this are interpreted as file-
              names.  This can be useful when viewing a file whose name begins
              with a "-" or "+".

       +      If  a  command  line option begins with +, the remainder of that
              option is taken to be an initial command to less.  For  example,
              +G  tells  less  to start at the end of the file rather than the
              beginning, and +/xyz tells it to start at the  first  occurrence
              of  "xyz"  in  the file.  As a special case, +<number> acts like
              +<number>g; that is, it starts the display at the specified line
              number  (however,  see  the caveat under the "g" command above).
              If the option starts with ++, the initial command applies to ev-
              ery  file  being  viewed, not just the first one.  The + command
              described previously may also be used to set (or change) an ini-
              tial command for every file.

LINE EDITING
       When  entering a command line at the bottom of the screen (for example,
       a filename for the :e command, or the pattern for  a  search  command),
       certain keys can be used to manipulate the command line.  Most commands
       have an alternate form in [ brackets ] which can be used if a key  does
       not  exist  on  a  particular keyboard.  (Note that the forms beginning
       with ESC do not work in some MS-DOS and Windows systems because ESC  is
       the  line  erase  character.)  Any of these special keys may be entered
       literally by preceding it with the "literal" character,  either  ^V  or
       ^A.   A  backslash itself may also be entered literally by entering two
       backslashes.

       LEFTARROW [ ESC-h ]
              Move the cursor one space to the left.

       RIGHTARROW [ ESC-l ]
              Move the cursor one space to the right.

       ^LEFTARROW [ ESC-b or ESC-LEFTARROW ]
              (That is, CONTROL and LEFTARROW simultaneously.)  Move the  cur-
              sor one word to the left.

       ^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ]
              (That is, CONTROL and RIGHTARROW simultaneously.)  Move the cur-
              sor one word to the right.

       HOME [ ESC-0 ]
              Move the cursor to the beginning of the line.

       END [ ESC-$ ]
              Move the cursor to the end of the line.

       BACKSPACE
              Delete the character to the left of the cursor,  or  cancel  the
              command if the command line is empty.

       DELETE or [ ESC-x ]
              Delete the character under the cursor.

       ^BACKSPACE [ ESC-BACKSPACE ]
              (That  is,  CONTROL  and  BACKSPACE simultaneously.)  Delete the
              word to the left of the cursor.

       ^DELETE [ ESC-X or ESC-DELETE ]
              (That is, CONTROL and DELETE simultaneously.)  Delete  the  word
              under the cursor.

       UPARROW [ ESC-k ]
              Retrieve  the  previous  command  line.  If you first enter some
              text and then press UPARROW, it will retrieve the previous  com-
              mand which begins with that text.

       DOWNARROW [ ESC-j ]
              Retrieve  the  next  command line.  If you first enter some text
              and then press DOWNARROW, it  will  retrieve  the  next  command
              which begins with that text.

       TAB    Complete  the partial filename to the left of the cursor.  If it
              matches more than one filename, the first match is entered  into
              the  command  line.   Repeated  TABs  will  cycle thru the other
              matching filenames.  If the completed filename is a directory, a
              "/"  is  appended to the filename.  (On MS-DOS systems, a "\" is
              appended.)  The environment variable LESSSEPARATOR can  be  used
              to specify a different character to append to a directory name.

       BACKTAB [ ESC-TAB ]
              Like, TAB, but cycles in the reverse direction thru the matching
              filenames.

       ^L     Complete the partial filename to the left of the cursor.  If  it
              matches more than one filename, all matches are entered into the
              command line (if they fit).

       ^U (Unix and OS/2) or ESC (MS-DOS)
              Delete the entire command line, or cancel  the  command  if  the
              command line is empty.  If you have changed your line-kill char-
              acter in Unix to something other than ^U, that character is used
              instead of ^U.

       ^G     Delete the entire command line and return to the main prompt.

KEY BINDINGS
       You  may  define your own less commands by using the program lesskey(1)
       to create a lesskey file.  This file specifies a set  of  command  keys
       and  an  action  associated with each key.  You may also use lesskey to
       change the line-editing keys (see LINE EDITING), and to set environment
       variables.   If the environment variable LESSKEY is set, less uses that
       as the name of the lesskey file.  Otherwise, less looks in  a  standard
       place  for  the lesskey file: On Unix systems, less looks for a lesskey
       file called "$HOME/.less".  On Windows systems,  less  looks
       for  a lesskey file called "$HOME/.less", and if it is not found there,
       then looks for a lesskey file called ".less" in any directory specified
       in  the  PATH  environment variable.  On MS-DOS and Windows systems,
       less  looks for  a lesskey file called "$HOME/_less", and if it is
       not found there, then looks for a lesskey file called "_less" in any directory
       specified in the PATH environment variable.  On OS/2 systems, less looks for a
       lesskey file called "$HOME/less.ini", and if  it  is  not  found,  then
       looks  for  a lesskey file called "less.ini" in any directory specified
       in the INIT environment variable, and if it not found there, then looks
       for  a lesskey file called "less.ini" in any directory specified in the
       PATH environment variable.  See the lesskey manual page  for  more  de-
       tails.

       A  system-wide lesskey file may also be set up to provide key bindings.
       If a key is defined in both a local lesskey file and in the system-wide
       file,  key bindings in the local file take precedence over those in the
       system-wide file.  If the environment variable LESSKEY_SYSTEM  is  set,
       less uses that as the name of the system-wide lesskey file.  Otherwise,
       less looks in a standard place for the  system-wide  lesskey  file:  On
       Unix  systems,  the system-wide lesskey file is /usr/local/etc/sysless.
       (However, if less was built with a  different  sysconf  directory  than
       /usr/local/etc, that directory is where the sysless file is found.)  On
       Windows systems, the system-wide lesskey  file  is  c:\ProgramData\less\sys-
       less.  On MS-DOS systems, the system-wide lesskey file is c:\_sysless.
       On OS/2 systems, the system-wide lesskey file is c:\sysless.ini.

INPUT PREPROCESSOR
       You  may  define an "input preprocessor" for less.  Before less opens a
       file, it first gives your input preprocessor a chance to modify the way
       the  contents of the file are displayed.  An input preprocessor is sim-
       ply an executable program (or shell script), which writes the  contents
       of the file to a different file, called the replacement file.  The con-
       tents of the replacement file are then displayed in place of  the  con-
       tents  of the original file.  However, it will appear to the user as if
       the original file is opened; that is, less will  display  the  original
       filename as the name of the current file.

       An  input preprocessor receives one command line argument, the original
       filename, as entered by the user.  It  should  create  the  replacement
       file,  and when finished, print the name of the replacement file to its
       standard output.  If the input preprocessor does not output a  replace-
       ment  filename, less uses the original file, as normal.  The input pre-
       processor is not called when viewing standard input.  To set up an  in-
       put  preprocessor,  set  the LESSOPEN environment variable to a command
       line which will invoke your  input  preprocessor.   This  command  line
       should  include  one  occurrence  of the string "%s", which will be re-
       placed by the filename when the input preprocessor command is invoked.

       When less closes a file opened in such a way, it will call another pro-
       gram,  called  the  input  postprocessor, which may perform any desired
       clean-up action (such as  deleting  the  replacement  file  created  by
       LESSOPEN).  This program receives two command line arguments, the orig-
       inal filename as entered by the user, and the name of  the  replacement
       file.   To set up an input postprocessor, set the LESSCLOSE environment
       variable to a command line which will invoke your input  postprocessor.
       It  may  include  two  occurrences of the string "%s"; the first is re-
       placed with the original name of the file and the second with the  name
       of the replacement file, which was output by LESSOPEN.

       For  example, on many Unix systems, these two scripts will allow you to
       keep files in compressed format, but still let less view them directly:

       lessopen.sh:
            #! /bin/sh
            case "$1" in
            *.Z) TEMPFILE=$(mktemp)
                 uncompress -c $1  >$TEMPFILE  2>/dev/null
                 if [ -s $TEMPFILE ]; then
                      echo $TEMPFILE
                 else
                      rm -f $TEMPFILE
                 fi
                 ;;
            esac

       lessclose.sh:
            #! /bin/sh
            rm $2

       To use these scripts, put them both where they can be executed and  set
       LESSOPEN="lessopen.sh %s",  and  LESSCLOSE="lessclose.sh %s %s".   More
       complex LESSOPEN and LESSCLOSE scripts may be written to  accept  other
       types of compressed files, and so on.

       It  is  also  possible to set up an input preprocessor to pipe the file
       data directly to less, rather than putting the data into a  replacement
       file.  This avoids the need to decompress the entire file before start-
       ing to view it.  An input preprocessor that works this way is called an
       input  pipe.   An input pipe, instead of writing the name of a replace-
       ment file on its standard output, writes the entire contents of the re-
       placement  file  on  its  standard  output.  If the input pipe does not
       write any characters on its standard output, then there is no  replace-
       ment  file and less uses the original file, as normal.  To use an input
       pipe, make the first character in the LESSOPEN environment  variable  a
       vertical  bar  (|)  to  signify that the input preprocessor is an input
       pipe.  As with non-pipe input preprocessors, the  command  string  must
       contain  one  occurrence  of %s, which is replaced with the filename of
       the input file.

       For example, on many Unix systems, this script will work like the  pre-
       vious example scripts:

       lesspipe.sh:
            #! /bin/sh
            case "$1" in
            *.Z) uncompress -c $1  2>/dev/null
                 ;;
            *)   exit 1
                 ;;
            esac
            exit $?

       To  use  this  script,  put  it  where  it  can  be  executed  and  set
       LESSOPEN="|lesspipe.sh %s".

       Note that a preprocessor cannot output an empty file, since that is in-
       terpreted  as meaning there is no replacement, and the original file is
       used.  To avoid this, if LESSOPEN starts with two  vertical  bars,  the
       exit  status  of  the script determines the behavior when the output is
       empty.  If the output is empty and the exit status is zero,  the  empty
       output  is  considered  to be replacement text.  If the output is empty
       and the exit status is nonzero, the original file is used.  For compat-
       ibility  with  previous  versions of less, if LESSOPEN starts with only
       one vertical bar, the exit status of the preprocessor is ignored.

       When an input pipe is used, a LESSCLOSE postprocessor can be used,  but
       it is usually not necessary since there is no replacement file to clean
       up.  In this case, the replacement file name passed  to  the  LESSCLOSE
       postprocessor is "-".

       For  compatibility with previous versions of less, the input preproces-
       sor or pipe is not used if less is viewing standard input.  However, if
       the  first  character of LESSOPEN is a dash (-), the input preprocessor
       is used on standard input as well as other files.  In  this  case,  the
       dash  is  not  considered  to  be part of the preprocessor command.  If
       standard input is being viewed, the input preprocessor is passed a file
       name  consisting of a single dash.  Similarly, if the first two charac-
       ters of LESSOPEN are vertical bar and dash (|-) or  two  vertical  bars
       and  a  dash (||-), the input pipe is used on standard input as well as
       other files.  Again, in this case the dash is not considered to be part
       of the input pipe command.

NATIONAL CHARACTER SETS
       There are three types of characters in the input file:

       normal characters
              can be displayed directly to the screen.

       control characters
              should  not  be displayed directly, but are expected to be found
              in ordinary text files (such as backspace and tab).

       binary characters
              should not be displayed directly and  are  not  expected  to  be
              found in text files.

       A "character set" is simply a description of which characters are to be
       considered normal, control, and binary.   The  LESSCHARSET  environment
       variable  may  be  used to select a character set.  Possible values for
       LESSCHARSET are:

       ascii  BS, TAB, NL, CR, and formfeed are control characters, all  chars
              with  values  between  32 and 126 are normal, and all others are
              binary.

       iso8859
              Selects an ISO 8859 character set.  This is the same  as  ASCII,
              except  characters  between  160  and  255 are treated as normal
              characters.

       latin1 Same as iso8859.

       latin9 Same as iso8859.

       dos    Selects a character set appropriate for MS-DOS.

       ebcdic Selects an EBCDIC character set.

       IBM-1047
              Selects an EBCDIC character set used by  OS/390  Unix  Services.
              This  is the EBCDIC analogue of latin1.  You get similar results
              by setting either LESSCHARSET=IBM-1047 or LC_CTYPE=en_US in your
              environment.

       koi8-r Selects a Russian character set.

       next   Selects a character set appropriate for NeXT computers.

       utf-8  Selects  the  UTF-8  encoding  of  the  ISO 10646 character set.
              UTF-8 is special in that it supports  multi-byte  characters  in
              the input file.  It is the only character set that supports mul-
              ti-byte characters.

       windows
              Selects a character set appropriate for  Microsoft  Windows  (cp
              1251).

       In  rare cases, it may be desired to tailor less to use a character set
       other than the ones definable by LESSCHARSET.  In this case, the  envi-
       ronment variable LESSCHARDEF can be used to define a character set.  It
       should be set to a string where each character in the string represents
       one  character  in  the character set.  The character "." is used for a
       normal character, "c" for control, and "b" for binary.  A decimal  num-
       ber  may  be  used  for  repetition.  For example, "bccc4b." would mean
       character 0 is binary, 1, 2 and 3 are control, 4, 5, 6 and 7 are  bina-
       ry, and 8 is normal.  All characters after the last are taken to be the
       same as the last, so characters 9 through 255 would be  normal.   (This
       is  an  example,  and does not necessarily represent any real character
       set.)

       This table shows the value of LESSCHARDEF which is equivalent  to  each
       of the possible values for LESSCHARSET:

            ascii      8bcccbcc18b95.b
            dos        8bcccbcc12bc5b95.b.
            ebcdic     5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b
                       9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b.
            IBM-1047   4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc
                       191.b
            iso8859    8bcccbcc18b95.33b.
            koi8-r     8bcccbcc18b95.b128.
            latin1     8bcccbcc18b95.33b.
            next       8bcccbcc18b95.bb125.bb

       If  neither  LESSCHARSET nor LESSCHARDEF is set, but any of the strings
       "UTF-8", "UTF8", "utf-8" or "utf8" is found in the LC_ALL, LC_CTYPE  or
       LANG environment variables, then the default character set is utf-8.

       If that string is not found, but your system supports the setlocale in-
       terface, less will use setlocale to determine the character set.   set-
       locale  is controlled by setting the LANG or LC_CTYPE environment vari-
       ables.

       Finally, if the setlocale interface is also not available, the  default
       character set is latin1.

       Control  and  binary  characters  are  displayed  in  standout (reverse
       video).  Each such character is displayed in caret notation if possible
       (e.g.  ^A for control-A).  Caret notation is used only if inverting the
       0100 bit results in a normal printable character.  Otherwise, the char-
       acter  is displayed as a hex number in angle brackets.  This format can
       be changed by setting the LESSBINFMT environment variable.   LESSBINFMT
       may begin with a "*" and one character to select the display attribute:
       "*k" is blinking, "*d" is bold, "*u" is underlined, "*s"  is  standout,
       and  "*n"  is  normal.  If LESSBINFMT does not begin with a "*", normal
       attribute is assumed.  The remainder of LESSBINFMT is  a  string  which
       may  include one printf-style escape sequence (a % followed by x, X, o,
       d, etc.).  For example, if LESSBINFMT is  "*u[%x]",  binary  characters
       are  displayed  in  underlined hexadecimal surrounded by brackets.  The
       default if no LESSBINFMT is specified is "*s<%02X>".  Warning: the  re-
       sult  of  expanding  the  character via LESSBINFMT must be less than 31
       characters.

       When the character set is utf-8, the LESSUTFBINFMT environment variable
       acts similarly to LESSBINFMT but it applies to Unicode code points that
       were successfully decoded but are unsuitable for display  (e.g.,  unas-
       signed  code  points).   Its  default  value is "<U+%04lX>".  Note that
       LESSUTFBINFMT and LESSBINFMT  share  their  display  attribute  setting
       ("*x")  so specifying one will affect both; LESSUTFBINFMT is read after
       LESSBINFMT so its setting, if any,  will  have  priority.   Problematic
       octets  in  a  UTF-8  file (octets of a truncated sequence, octets of a
       complete but non-shortest form  sequence,  invalid  octets,  and  stray
       trailing  octets)  are displayed individually using LESSBINFMT so as to
       facilitate diagnostic of how the UTF-8 file is ill-formed.

PROMPTS
       The -P option allows you to tailor the prompt to your preference.   The
       string  given  to  the  -P option replaces the specified prompt string.
       Certain characters in the string are interpreted specially.  The prompt
       mechanism  is  rather complicated to provide flexibility, but the ordi-
       nary user need not understand the details of constructing  personalized
       prompt strings.

       A  percent sign followed by a single character is expanded according to
       what the following character is:

       %bX    Replaced by the byte offset into the current input file.  The  b
              is followed by a single character (shown as X above) which spec-
              ifies the line whose byte offset is to be used.  If the  charac-
              ter  is a "t", the byte offset of the top line in the display is
              used, an "m" means use the middle line, a "b" means use the bot-
              tom  line,  a "B" means use the line just after the bottom line,
              and a "j" means use the "target" line, as specified  by  the  -j
              option.

       %B     Replaced by the size of the current input file.

       %c     Replaced by the column number of the text appearing in the first
              column of the screen.

       %dX    Replaced by the page number of a line in the  input  file.   The
              line to be used is determined by the X, as with the %b option.

       %D     Replaced  by  the  number of pages in the input file, or equiva-
              lently, the page number of the last line in the input file.

       %E     Replaced by the name of the editor (from the VISUAL  environment
              variable,  or  the  EDITOR environment variable if VISUAL is not
              defined).  See the discussion of the LESSEDIT feature below.

       %f     Replaced by the name of the current input file.

       %F     Replaced by the last component of the name of the current  input
              file.

       %g     Replaced  by  the  shell-escaped name of the current input file.
              This is useful when the expanded string will be used in a  shell
              command, such as in LESSEDIT.

       %i     Replaced  by  the index of the current file in the list of input
              files.

       %lX    Replaced by the line number of a line in the  input  file.   The
              line to be used is determined by the X, as with the %b option.

       %L     Replaced by the line number of the last line in the input file.

       %m     Replaced by the total number of input files.

       %pX    Replaced  by  the  percent into the current input file, based on
              byte offsets.  The line used is determined by the X as with  the
              %b option.

       %PX    Replaced  by  the  percent into the current input file, based on
              line numbers.  The line used is determined by the X as with  the
              %b option.

       %s     Same as %B.

       %t     Causes  any  trailing spaces to be removed.  Usually used at the
              end of the string, but may appear anywhere.

       %T     Normally expands to the word "file".  However if  viewing  files
              via  a  tags  list  using  the -t option, it expands to the word
              "tag".

       %x     Replaced by the name of the next input file in the list.

       If any item is unknown (for example, the file size if input is a pipe),
       a question mark is printed instead.

       The  format  of  the  prompt string can be changed depending on certain
       conditions.  A question mark followed by a single character  acts  like
       an  "IF": depending on the following character, a condition is evaluat-
       ed.  If the condition is true, any characters  following  the  question
       mark  and  condition  character,  up  to  a period, are included in the
       prompt.  If the condition is false, such characters are  not  included.
       A  colon appearing between the question mark and the period can be used
       to establish an "ELSE": any characters between the colon and the period
       are  included  in  the string if and only if the IF condition is false.
       Condition characters (which follow a question mark) may be:

       ?a     True if any characters have been included in the prompt so far.

       ?bX    True if the byte offset of the specified line is known.

       ?B     True if the size of current input file is known.

       ?c     True if the text is horizontally shifted (%c is not zero).

       ?dX    True if the page number of the specified line is known.

       ?e     True if at end-of-file.

       ?f     True if there is an input filename (that is, if input is  not  a
              pipe).

       ?lX    True if the line number of the specified line is known.

       ?L     True if the line number of the last line in the file is known.

       ?m     True if there is more than one input file.

       ?n     True if this is the first prompt in a new input file.

       ?pX    True  if  the percent into the current input file, based on byte
              offsets, of the specified line is known.

       ?PX    True if the percent into the current input file, based  on  line
              numbers, of the specified line is known.

       ?s     Same as "?B".

       ?x     True  if there is a next input file (that is, if the current in-
              put file is not the last one).

       Any characters other than the special ones (question mark, colon, peri-
       od,  percent,  and backslash) become literally part of the prompt.  Any
       of the special characters may be included in the  prompt  literally  by
       preceding it with a backslash.

       Some examples:

       ?f%f:Standard input.

       This  prompt prints the filename, if known; otherwise the string "Stan-
       dard input".

       ?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-...

       This prompt would print the filename, if known.  The filename  is  fol-
       lowed  by  the  line  number, if known, otherwise the percent if known,
       otherwise the byte offset if known.  Otherwise, a dash is printed.  No-
       tice  how each question mark has a matching period, and how the % after
       the %pt is included literally by escaping it with a backslash.

       ?n?f%f .?m(%T %i of %m) ..?e(END) ?x- Next\: %x..%t";

       This prints the filename if this is the first prompt in  a  file,  fol-
       lowed  by  the  "file  N  of N" message if there is more than one input
       file.  Then, if we are at end-of-file, the string  "(END)"  is  printed
       followed  by  the name of the next file, if there is one.  Finally, any
       trailing spaces are truncated.  This is the default prompt.  For refer-
       ence,  here  are  the defaults for the other two prompts (-m and -M re-
       spectively).  Each is broken into two lines here for readability only.

       ?n?f%f .?m(%T %i of %m) ..?e(END) ?x- Next\: %x.:
               ?pB%pB\%:byte %bB?s/%s...%t

       ?f%f .?n?m(%T %i of %m) ..?ltlines %lt-%lb?L/%L. :
               byte %bB?s/%s. .?e(END) ?x- Next\: %x.:?pB%pB\%..%t

       And here is the default message produced by the = command:

       ?f%f .?m(%T %i of %m) .?ltlines %lt-%lb?L/%L. .
               byte %bB?s/%s. ?e(END) :?pB%pB\%..%t

       The prompt expansion features are also used for another purpose: if  an
       environment  variable LESSEDIT is defined, it is used as the command to
       be executed when the v command is invoked.  The LESSEDIT string is  ex-
       panded  in  the  same way as the prompt strings.  The default value for
       LESSEDIT is:

               %E ?lm+%lm. %g

       Note that this expands to the editor name, followed by a + and the line
       number,  followed  by the shell-escaped file name.  If your editor does
       not accept the "+linenumber" syntax, or has other differences in  invo-
       cation  syntax, the LESSEDIT variable can be changed to modify this de-
       fault.

SECURITY
       When the environment variable LESSSECURE is set to 1, less  runs  in  a
       "secure" mode.  This means these features are disabled:

              !      the shell command

              |      the pipe command

              :e     the examine command.

              v      the editing command

              s  -o  log files

              -k     use of lesskey files

              -t     use of tags files

                     metacharacters in filenames, such as *

                     filename completion (TAB, ^L)

                     history file

       Less can also be compiled to be permanently in "secure" mode.

COMPATIBILITY WITH MORE
       If the environment variable LESS_IS_MORE is set to 1, or if the program
       is invoked via a file link named "more", less behaves (mostly) in  con-
       formance  with  the  POSIX "more" command specification.  In this mode,
       less behaves differently in these ways:

       The -e option works differently.  If the -e option is not set, less be-
       haves  as if the -e option were set.  If the -e option is set, less be-
       haves as if the -E option were set.

       The -m option works differently.  If the -m  option  is  not  set,  the
       medium  prompt  is used, and it is prefixed with the string "--More--".
       If the -m option is set, the short prompt is used.

       The -n option acts like the -z option.  The normal behavior of  the  -n
       option is unavailable in this mode.

       The  parameter  to  the  -p option is taken to be a less command rather
       than a search pattern.

       The LESS environment variable is  ignored,  and  the  MORE  environment
       variable is used in its place.

ENVIRONMENT VARIABLES
       Environment variables may be specified either in the system environment
       as usual, or in a lesskey(1) file.  If environment  variables  are  de-
       fined in more than one place, variables defined in a local lesskey file
       take precedence over variables defined in the system environment, which
       take precedence over variables defined in the system-wide lesskey file.

       COLUMNS
              Sets the number of columns on the screen.  Takes precedence over
              the number of columns specified by the TERM variable.   (But  if
              you  have  a  windowing  system  which  supports  TIOCGWINSZ  or
              WIOCGETD, the window system's idea  of  the  screen  size  takes
              precedence over the LINES and COLUMNS environment variables.)

       EDITOR The name of the editor (used for the v command).

       HOME   Name  of  the user's home directory (used to find a lesskey file
              on Unix and OS/2 systems).

       HOMEDRIVE, HOMEPATH
              Concatenation of the HOMEDRIVE and  HOMEPATH  environment  vari-
              ables is the name of the user's home directory if the HOME vari-
              able is not set (only in the Windows version).

       INIT   Name of the user's init directory (used to find a  lesskey  file
              on OS/2 systems).

       LANG   Language for determining the character set.

       LC_CTYPE
              Language for determining the character set.

       LESS   Options which are passed to less automatically.

       LESSANSIENDCHARS
              Characters  which may end an ANSI color escape sequence (default
              "m").

       LESSANSIMIDCHARS
              Characters which may appear between the ESC  character  and  the
              end   character  in  an  ANSI  color  escape  sequence  (default
              "0123456789:;[?!"'#%()*+ ".

       LESSBINFMT
              Format for displaying non-printable, non-control characters.

       LESSCHARDEF
              Defines a character set.

       LESSCHARSET
              Selects a predefined character set.

       LESSCLOSE
              Command line to invoke the (optional) input-postprocessor.

       LESSECHO
              Name of the lessecho program (default "lessecho").  The lessecho
              program  is needed to expand metacharacters, such as * and ?, in
              filenames on Unix systems.

       LESSEDIT
              Editor prototype string (used for the v command).   See  discus-
              sion under PROMPTS.

       LESSGLOBALTAGS
              Name  of  the command used by the -t option to find global tags.
              Normally should be set to "global" if your system has the  glob-
              al(1) command.  If not set, global tags are not used.

       LESSHISTFILE
              Name  of  the  history file used to remember search commands and
              shell commands between invocations of less.  If set  to  "-"  or
              "/dev/null",  a  history  file  is  not  used.   The  default is
              "$HOME/.lesshst" on Unix or Windows systems, "$HOME/_lesshst" on DOS
              systems,  or "$HOME/lesshst.ini" or "$INIT/lesshst.ini" on OS/2 systems.

       LESSHISTSIZE
              The maximum number of commands to save in the history file.  The
              default is 100.

       LESSKEYIN
              Name of the default lesskey source file.

       LESSKEY
              Name  of  the  default  lesskey  binary  file.  (Not   used   if
              "$LESSKEYIN" exists.)

       LESSKEYIN_SYSTEM
              Name of the default system-wide lesskey source file.

       LESSKEY_SYSTEM
              Name  of  the default system-wide lesskey binary file. (Not used
              if "$LESSKEYIN_SYSTEM" exists.)

       LESSMETACHARS
              List of characters which are considered "metacharacters" by  the
              shell.

       LESSMETAESCAPE
              Prefix  which  less will add before each metacharacter in a com-
              mand sent to the shell.  If LESSMETAESCAPE is an  empty  string,
              commands  containing  metacharacters  will  not be passed to the
              shell.

       LESSOPEN
              Command line to invoke the (optional) input-preprocessor.

       LESSSECURE
              Runs less in "secure" mode.  See discussion under SECURITY.

       LESSSEPARATOR
              String to be appended to a directory name  in  filename  comple-
              tion.

       LESSUTFBINFMT
              Format for displaying non-printable Unicode code points.

       LESS_IS_MORE
              Emulate the more(1) command.

       LINES  Sets  the  number of lines on the screen.  Takes precedence over
              the number of lines specified by the TERM variable.  (But if you
              have  a  windowing system which supports TIOCGWINSZ or WIOCGETD,
              the window system's idea of the  screen  size  takes  precedence
              over the LINES and COLUMNS environment variables.)

       MORE   Options  which  are passed to less automatically when running in
              more compatible mode.

       PATH   User's search path (used to find a lesskey file  on  MS-DOS  and
              OS/2 systems).

       SHELL  The  shell  used  to execute the ! command, as well as to expand
              filenames.

       TERM   The type of terminal on which less is being run.

       VISUAL The name of the editor (used for the v command).

SEE ALSO
       lesskey(1)

COPYRIGHT
       Copyright (C) 1984-2022  Mark Nudelman

       less is part of the GNU project and is free software.  You  can  redis-
       tribute  it and/or modify it under the terms of either (1) the GNU Gen-
       eral Public License as published by the Free  Software  Foundation;  or
       (2) the Less License.  See the file README in the less distribution for
       more details regarding redistribution.  You should have received a copy
       of  the  GNU General Public License along with the source for less; see
       the file COPYING.  If not, write to the Free  Software  Foundation,  59
       Temple  Place, Suite 330, Boston, MA  02111-1307, USA.  You should also
       have received a copy of the Less License; see the file LICENSE.

       less is distributed in the hope that it will be useful, but WITHOUT ANY
       WARRANTY;  without even the implied warranty of MERCHANTABILITY or FIT-
       NESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License  for
       more details.

AUTHOR
       Mark Nudelman
       Report bugs at https://github.com/gwsw/less/issues.
       For more information, see the less homepage at
       https://greenwoodsoftware.com/less



                           Version 608: 22 Jul 2022                    LESS(1)