Show HN: Linux CLI tool to provide mutex locks for long running bash ops (opens in new tab)

(github.com)

34 pointsbigattichouse8mo ago20 comments

Been exploring claude and spec-based coding, I think it turned out fairly successful. It's just a simple unix-style tool that gives you a single command to use in bash scripts to simplify mutex or semaphore locking of execution.

20 comments

sluongng8mo ago

Why not https://man7.org/linux/man-pages/man2/flock.2.html?

yjftsjthsd-h8mo ago

Nit: Probably https://man7.org/linux/man-pages/man1/flock.1.html (shell command, not the underlying libc function)

anitil8mo ago

This was my first thought and I suppose flock(1) could be used to recreate a lot of this. But it does come with some other quality-of-life improvements like being able to list all currently-used locks, having a lock holdable by N processes etc.

Zacru8mo ago

Because that's a syscall ;) https://man7.org/linux/man-pages/man1/flock.1.html is the command line manual.

I would say one good reason is that

  waitlock myapp &
  JOB_PID=$!
  # ... do exclusive work ...
  kill $JOB_PID

is a lot easier to use and remember than

  (; flock -n 9 || exit 1; # ... commands executed under lock ...; ) 9>/var/lock/mylockfile

yjftsjthsd-h8mo ago

Why

  (; flock -n 9

and not

  ( flock -n 9

?

1 more reply

permalac8mo ago

Flock can be used in a single line for example for cronjobs.

Flock -s file && script.

Pretty simple. (I forgot the argument, I think is -s..

bigattichouseOP8mo ago

just pushed a change so now it's:

waitlock myapp & #... do stuff waitlock --done myapp

ethan_smith8mo ago

flock is indeed built-in: `flock -xn /tmp/mylock.lock -c "echo running locked command"` does mutex locking in bash. Your tool might offer better ergonomics or features beyond flock's capabilities?

teddyh8mo ago

We already have lockfile: <https://manpages.debian.org/stable/procmail/lockfile.1.en.ht...>.

forrestthewoods8mo ago

I don’t know the exact threshold at which you should use a real programming language instead of a bash script. But this type of work definitely exceeds it.

anitil8mo ago

While in general I'd agree, this isn't necessarily just for bash scripts. It could just wrap the execution of another program allowing higher-level logic to handle concurrency and the low-level program to do it's one-at-a-time job

bigattichouseOP8mo ago

Sometimes you have a cron job that takes longer than it should (but inconsistently so), and another cron job that clobbers what that cron job is doing.

asddfgg558mo ago

Useful project, I love all things terminal, so I also enjoyed your project.

eddythompson808mo ago

You enjoyed the project because you love the terminal?

bigattichouseOP8mo ago

Good enough for me. I created the project because I love terminal, and wanted to make something using Claude (to learn how this tool works, strictly for personal enrichment) that solves a small problem I had with some overlapping cron job management.

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20 comments

sluongng8mo ago

Why not https://man7.org/linux/man-pages/man2/flock.2.html?

yjftsjthsd-h8mo ago

Nit: Probably https://man7.org/linux/man-pages/man1/flock.1.html (shell command, not the underlying libc function)

anitil8mo ago

Zacru8mo ago

Because that's a syscall ;) https://man7.org/linux/man-pages/man1/flock.1.html is the command line manual.

I would say one good reason is that

  waitlock myapp &
  JOB_PID=$!
  # ... do exclusive work ...
  kill $JOB_PID

is a lot easier to use and remember than

  (; flock -n 9 || exit 1; # ... commands executed under lock ...; ) 9>/var/lock/mylockfile

yjftsjthsd-h8mo ago

Why

  (; flock -n 9

and not

  ( flock -n 9

?

1 more reply

permalac8mo ago

Flock can be used in a single line for example for cronjobs.

Flock -s file && script.

Pretty simple. (I forgot the argument, I think is -s..

bigattichouseOP8mo ago

just pushed a change so now it's:

waitlock myapp & #... do stuff waitlock --done myapp

ethan_smith8mo ago

flock is indeed built-in: `flock -xn /tmp/mylock.lock -c "echo running locked command"` does mutex locking in bash. Your tool might offer better ergonomics or features beyond flock's capabilities?

teddyh8mo ago

We already have lockfile: <https://manpages.debian.org/stable/procmail/lockfile.1.en.ht...>.

forrestthewoods8mo ago

I don’t know the exact threshold at which you should use a real programming language instead of a bash script. But this type of work definitely exceeds it.

anitil8mo ago

bigattichouseOP8mo ago

Sometimes you have a cron job that takes longer than it should (but inconsistently so), and another cron job that clobbers what that cron job is doing.

asddfgg558mo ago

Useful project, I love all things terminal, so I also enjoyed your project.

eddythompson808mo ago

You enjoyed the project because you love the terminal?

bigattichouseOP8mo ago

1 more reply

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