Bug #19130: MRI failing when executing shell builtin commands with Errno::ENOENT

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: 3.2.0
• Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN

[ifiht (Mikal R)]

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.

[ifiht (Mikal R)]

• Subject changed from MRI failing when executing shell builtins with Errno::ENOENT to MRI failing when executing shell builtin commands with Errno::ENOENT
• Description updated (diff)

[mjrzasa (Maciek Rząsa)]

I've reproduced it on MRI 2.7.0, but not for all built-ins, just ones that are Bash-specific as per these lists:

• https://www.gnu.org/software/bash/manual/html_node/Bourne-Shell-Builtins.html (these work)
• https://www.gnu.org/software/bash/manual/html_node/Bash-Builtins.html (these fail)

[3] pry(main)> %x(type ls)
Errno::ENOENT: No such file or directory - type
from (pry):3:in ``'
[4] pry(main)> %x(pwd)
=> "/home/mrzasa\n"
[5] pry(main)> %x(return)
=> ""
[6] pry(main)> %x(alias)
Errno::ENOENT: No such file or directory - alias
from (pry):6:in ``'

[ifiht (Mikal R)]

Is there a ruby-specific list then of what gets implemented? Seems like type is both included in the POSIX spec (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/type.html) and the Bourne Shell, but not Ruby:

└$ /bin/sh -c "type type"
type is a shell builtin

[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:

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

[nobu (Nobuyoshi Nakada)]

ifiht (Mikal R) wrote in #note-3:

Is there a ruby-specific list then of what gets implemented? Seems like type is both included in the POSIX spec (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/type.html) and the Bourne Shell, but not Ruby:

The list in Ruby is based on http://pubs.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html,
and may be pretty out of date.

jeremyevans0 (Jeremy Evans) wrote in #note-4:

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

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

Or include a semicolon:

%x{type type;}

[nobu (Nobuyoshi Nakada)]

nobu (Nobuyoshi Nakada) wrote in #note-5:

The list in Ruby is based on http://pubs.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html,
and may be pretty out of date.

FYI, this list is here: https://github.com/ruby/ruby/blob/50c6cab/process.c#L2659-L2689

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed

Closing as this behavior is by design and not a bug.