Setup

$ ruby --version
ruby 2.7.1p83 (2020-03-31 revision a0c7c23c9c) [x86_64-darwin18]
$ pry --version
Pry version 0.13.1 on Ruby 2.7.1

Expected

In a file called system_call_exit_status.rb, I have the following:

system "exit 1"
puts "-- $? => #{$?}"
puts "-- $?.success? => #{$?.success?}"

which outputs

$ ruby system_call_exit_status.rb
-- $? => pid 94141 exit 1
-- $?.success? => false

The example above seem to demonstrate that system writes the exit status to $?, as described in documentation

Similar output can be seen by invoking pry on the file, i.e.

$ pry system_call_exit_status.rb
-- $? => pid 94141 exit 1
-- $?.success? => false

I would expect pry REPL to behave the same.

Actual

Unfortunately, the actual output from pry REPL seem to be different:

[1] pry(main)> system "exit 1"
=> false
[2] pry(main)> puts "-- $? => #{$?}"
-- $? => pid 94155 exit 0
=> nil
[3] pry(main)> puts "-- $?.success? => #{$?.success?}"
-- $?.success? => true
=> nil

Is this expected? I'm guessing pry REPL session overrides $? on calls to system, because using backticks seem to show accurate behavior, i.e.

[1] pry(main)> `exit 1`
=> ""
[2] pry(main)> puts "-- $? => #{$?}"
-- $? => pid 94156 exit 1
=> nil
[3] pry(main)> puts "-- $?.success? => #{$?.success?}"
-- $?.success? => false
=> nil