[ruby-core:110822] [Ruby master Bug#19130] MRI failing when executing shell builtin commands with Errno::ENOENT

["jeremyevans0 (Jeremy Evans)" <noreply@ruby-lang.org>]

Issue #19130 has been updated by jeremyevans0 (Jeremy Evans).


I don't think this is a bug.  Ruby's behavior for the Kernel backtick method (what `%x` uses) is that a shell is only used if Ruby thinks it is necessary.  If Ruby doesn't determine the use of a shell is necessary, it will directly execute the program instead of using a shell.  Here's an example showing the behavior:

```
# Simple command line that Ruby doesn't use a shell for
$ ruby -e 'puts %x{ps al}.split("\n").grep(/#{$$}/)'
 1000 54241 42309   3   2   0 61228 15220 kqread  S+     pi    0:00.14 ruby -e puts %x{ps al}.split("\\n").grep(/#{$$}/) (ruby31)
 1000 24047 54241   3  31   0   736   756 -       R+pU/0 pi    0:00.00 ps -al

# Command line including pipe, which Ruby does use a shell for
$ ruby -e 'puts %x{ps al | grep #{$$}}'
 1000 37783 42309   3   2   0 61228 15224 kqread  S+     pi    0:00.14 ruby -e puts %x{ps al | grep #{$$}} (ruby31)
 1000 95607 37783   3  18   0   872   880 sigsusp S+p    pi    0:00.01 sh -c ps al | grep 37783
 1000 47178 95607   3  31   0   172   460 -       R+/2   pi    0:00.00 grep 37783
```

If you want to force the use of a shell when would not be used, you need to manually execute the shell:

```ruby
%x{sh -c "type type"}
# => "type is a shell builtin\n"
```

----------------------------------------
Bug #19130: MRI failing when executing shell builtin commands with Errno::ENOENT
https://bugs.ruby-lang.org/issues/19130#change-100179

* Author: ifiht (Mikal R)
* Status: Open
* Priority: Normal
* ruby -v: 3.2.0
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN
----------------------------------------
Sorry if this came up already, Google & Redmine came up blank but maybe I missed it. Bug was found on 3.0.0 but I tested on 3.2.0-preview1 and it's present on both.

Trying to execute any shell builtin commands from irb or script fails with `No such file or directory - <cmd> (Errno::ENOENT)`

```
└$ rvm list
 * ruby-3.0.0 [ x86_64 ]
=> ruby-3.2.0-preview1 [ x86_64 ]
```
MRI 3.0.0:
```
3.0.0 :001 > %x(type ls)
Traceback (most recent call last):
        5: from /home/ifiht/.rvm/rubies/ruby-3.0.0/bin/irb:23:in `<main>'
        4: from /home/ifiht/.rvm/rubies/ruby-3.0.0/bin/irb:23:in `load'
        3: from /home/ifiht/.rvm/rubies/ruby-3.0.0/lib/ruby/gems/3.0.0/gems/irb-1.3.0/exe/irb:11:in `<top (required)>'
        2: from (irb):1:in `<main>'
        1: from (irb):1:in ``'
Errno::ENOENT (No such file or directory - type)
3.0.0 :002 > %x(cd /home/ifiht)
Traceback (most recent call last):
        6: from /home/ifiht/.rvm/rubies/ruby-3.0.0/bin/irb:23:in `<main>'
        5: from /home/ifiht/.rvm/rubies/ruby-3.0.0/bin/irb:23:in `load'
        4: from /home/ifiht/.rvm/rubies/ruby-3.0.0/lib/ruby/gems/3.0.0/gems/irb-1.3.0/exe/irb:11:in `<top (required)>'
        3: from (irb):1:in `<main>'
        2: from (irb):2:in `rescue in <main>'
        1: from (irb):2:in ``'
Errno::ENOENT (No such file or directory - cd)
3.0.0 :003 > exit
```
MRI 3.2.0:
```
:001 > %x(type ls)
(irb):1:in ``': No such file or directory - type (Errno::ENOENT)
        from (irb):1:in `<main>'
        from /home/ifiht/.rvm/rubies/ruby-3.2.0-preview1/lib/ruby/gems/3.2.0+1/gems/irb-1.4.1/exe/irb:11:in `<top (required)>'
        from /home/ifiht/.rvm/rubies/ruby-3.2.0-preview1/bin/irb:25:in `load'
        from /home/ifiht/.rvm/rubies/ruby-3.2.0-preview1/bin/irb:25:in `<main>'
 :002 > `type ls`
(irb):2:in ``': No such file or directory - type (Errno::ENOENT)
        from (irb):2:in `<main>'
        from /home/ifiht/.rvm/rubies/ruby-3.2.0-preview1/lib/ruby/gems/3.2.0+1/gems/irb-1.4.1/exe/irb:11:in `<top (required)>'
        from /home/ifiht/.rvm/rubies/ruby-3.2.0-preview1/bin/irb:25:in `load'
        from /home/ifiht/.rvm/rubies/ruby-3.2.0-preview1/bin/irb:25:in `<main>'
```

Assuming this is a bug? Let me know if shell builtins are deliberately excluded for some reason, I'll try to work around it.



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