The -c option behaves differently to Linux about flock HOT 10 OPEN

ah, well that use case convinces me. I'd usually this pattern for that use case, but that's obnoxious for one-offs.

ok, I'll look into implementing this.

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Great, I'll see how they're executing. I was a little afraid of entering n levels of encoding hell, so I just pass arguments along to execvp, see https://github.com/discoteq/flock/blob/master/src/flock.c#L304

I'm not sure I agree that linux-utils behaviour is what is most reasonable, but compatibility trumps sanity, right?

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Ah, they're being "smart" and passing along to a subshell: https://github.com/karelzak/util-linux/blob/master/sys-utils/flock.c#L239

Can you find one other person to agree this is the appropriate behaviour? I'm torn.

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Looks like it was added back in util-linux/util-linux@baf39af#diff-1219b3b65dcec8078370f245769671b1R193

And the only explanation in its NEWS is:

• flock: replaced with flock-2.0.2 by H. Peter Anvin

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maybe if it's a single string, pass to a subshell; if it's multiple, exec directly? I feel like something has similar behaviour but I can't remember what.

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Hi @josephholsten

Thanks for looking into this.

I think the -c option is to allow the caller have some symbols that would otherwise be interpreted by the shell.

flock -x file.lock cat id_rsa.pub >> authorized_keys

vs

flock -x file.lock -c 'cat id_rsa.pub >> authorized_keys'

In the first case above, the output of flock is appended to authorized_keys, outside of the lock; in the second case, the contents of id_rsa.pub are appended to authorized_keys inside the lock.

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+1

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so sorry, I dropped this right on the floor. I know I can't get to this till at least this evening, so here are my notes:

At the moment, -c is just grabbing the command from getopt_long():

cmd_argv = &argv[optind + 1];

and tossing it straight into execvp()

			if (0 != execvp(cmd_argv[0], cmd_argv)) {

so I really just want to build a new cmd_argv with cmd_argv[0] = getenv("SHELL") || "/bin/sh", cmd_argv[1] = "-c", then push the rest in.

Needs doc, especially to say that you can SHELL=/bin/wtfsh to specify your own.

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Yes, please implement this, it prevents it from being a 'drop in replacement' with some scripts i have :(

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If this is interesting to you, please review the implementation in #23

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