Command "brew update" shows "/dev/stdin: No such file or directory - /tmp/sh-thd-2853475760 (deleted) (Errno::ENOENT)" about brew

[MikeMcQuaid]

How are you running this? SSH?

[azhongzl]

Steps to reproduce:

1. launch iTerm2 on Mac
2. ssh to the remote host
3. run command brew update

Same happens if I

1. launch dcv-viewer and connect to the remote host
2. launch a terminal
3. run command brew update

It worked before but just failed recently

[MikeMcQuaid]

@azhongzl Can you reproduce on any other hosts or Linux machines? How long has this been happening? What user are you running as?

[azhongzl]

How long has this been happening?

It worked before but just started to fail yesterday

What user are you running as?

I run with my own user but should have every permissions.

[Bo98]

Sounds like something weird is happening with the way your system interacts with herestrings.

I'm guessing changing

brew/Library/Homebrew/utils/lock.sh

Lines 50 to 52 in f0e442d

	if [[ -x "${ruby}" ]] && "${ruby}" /dev/stdin <<<"exit(RUBY_VERSION >= '1.8.7')"
	then
	"${ruby}" /dev/stdin <<<"File.new(${lock_fd}).flock(File::LOCK_EX | File::LOCK_NB) || exit(1)"

to be (echo "exit(RUBY_VERSION >= '1.8.7')" | "${ruby}" /dev/stdin) might fix things? And similarly on the line below.

[azhongzl]

Thanks @Bo98. So the issue is caused by using an old version of ruby.

/usr/bin/ruby is hardcoded in above code.

brew/Library/Homebrew/utils/lock.sh

Line 42 in f0e442d

local ruby="/usr/bin/ruby"

In my env, /usr/bin/ruby is old

/usr/bin/ruby -v
ruby 2.0.0p648 (2015-12-16) [x86_64-linux]

The one on the path is latest

ruby -v
ruby 2.7.8p225 (2023-03-30 revision 1f4d455848) [x86_64-linux]

Run with old ruby, there are errors:

/usr/bin/ruby /dev/stdin <<< "exit(RUBY_VERSION >= '1.8.7')"
/dev/stdin: No such file or directory - /tmp/zshFl0HSh (deleted) (Errno::ENOENT)

Run with latest ruby, no issues:

ruby /dev/stdin <<< "exit(RUBY_VERSION >= '1.8.7')"

Can brew code use the default ruby on path instead of hardcoding?

[Bo98]

Maybe, though ideally we'd fix 2.0 otherwise we would need to bump the 1.8.7 requirement (though the requirement check itself is broken which is not good).

There's perhaps also an argument of hoisting the flock condition to the top:

brew/Library/Homebrew/utils/lock.sh

Lines 56 to 58 in f0e442d

	elif [[ -x "$(type -P flock)" ]]
	then
	flock -n "${lock_fd}"