Issue #11637: Used Shellcheck to resolve SC2236 in Shell Script

.ci/checkchmod.sh

@@ -8,7 +8,7 @@ CHMOD=$(find -type f -not -path '*/\.git/*' \
           -a -type f -not -name '*.sh' \
           -a -type f -not -name '*.pl' \
           -a \( -type d -not -perm 775 -o -type f -executable \))
-if [[ ! -z $CHMOD ]]; then
+if [[ -n $CHMOD ]]; then
     echo "Expected mode for non '.sh' files is 664.";
     echo "Files that violates this rule:"
     for NAMEFILE in $CHMOD
@@ -20,7 +20,7 @@ fi
 
 # On Travis, after clone, all 'sh' files have executable bit
 CHMOD=$(find -type f -not -path '*/\.git/*' -a -type f -name '*.sh' -a -not -executable)
-if [[ ! -z $CHMOD ]]; then
+if [[ -n $CHMOD ]]; then
     echo "Expected mode for '.sh' files is 755.";
     echo "Files that violates this rule:"
     for NAMEFILE in $CHMOD

.ci/no_old_refs.sh

@@ -14,7 +14,7 @@ MAIN_REPO="checkstyle/checkstyle"
 DEFAULT_BRANCH="master"
 
 # These are modified when event is of type pull_request
-if [ ! -z "$PR_HEAD_REPO_NAME" ]; then
+if [ -n "$PR_HEAD_REPO_NAME" ]; then
   MAIN_REPO=$PR_HEAD_REPO_NAME
   DEFAULT_BRANCH=$GITHUB_HEAD_REF
 fi
@@ -43,7 +43,7 @@ for MENTIONED_ISSUES_GREP_OUTPUT_LINE in $(cat $MENTIONED_ISSUES_GREP_OUTPUT); d
   if [ "$STATE" = "closed" ]; then
     echo "$LINK" >> $CLOSED_ISSUES
   fi
-  if [ ! -z "$LINKED_ISSUES" ]; then
+  if [ -n "$LINKED_ISSUES" ]; then
     for LINKED_ISSUE in $(cat "$LINKED_ISSUES"); do
       if [ "$LINKED_ISSUE" = "$GITHUB_HOST/$ISSUE" ]; then
         echo "$LINK" >> $LINKED_ISSUES_MENTIONED

.github/workflows/no_old_refs.yml

@@ -39,7 +39,7 @@ jobs:
           LINKED_ISSUES=${{ steps.links.outputs.issues }}
           LINKED_ISSUES_FORMATTED=/tmp/linked_issues
           CHECKSTYLE_ISSUE_URL="https:\/\/github.com\/checkstyle\/checkstyle\/issues\/"
-          if [ ! -z "$LINKED_ISSUES" ]; then
+          if [ -n "$LINKED_ISSUES" ]; then
             echo $LINKED_ISSUES | sed -e 's/,/\n/g' >> $LINKED_ISSUES_FORMATTED
             sed -i "s/^/$CHECKSTYLE_ISSUE_URL/" $LINKED_ISSUES_FORMATTED
           fi

.shellcheckrc

@@ -6,7 +6,6 @@ disable=SC2207 # (warning): Prefer mapfile or read -a to split command output.
 disable=SC2002 # (style): Useless cat. Consider 'cmd < file | ..' or 'cmd file | ..' instead.
 disable=SC2061 # (warning): Quote the parameter to -name so the shell won't interpret it.
 disable=SC2035 # (info): Use ./glob or -- glob so names with dashes won't become options.
-disable=SC2236 # (style): Use -n instead of ! -z.
 disable=SC2016 # (info): Expressions don't expand in single quotes, use double quotes for that.
 disable=SC2185 # (info): Some finds don't have a default path. Specify '.' explicitly.
 disable=SC2155 # (warning): Declare and assign separately to avoid masking return values.