Well, you want xargs as soon as your project is big, because you'll reach the limits on arguments fairly quickly.

I won't go too deep on the issues this will trigger if your filenames contain special characters. We often think of spaces, but you could have some nastier stuff. If you want to sound smart at your next geeks reunion, simply read http://www.dwheeler.com/essays/fixing-unix-linux-filenames.h...

On (modern, i.e. 2.6.23 and later) Linux at least, you won't hit them quickly:

    $ getconf ARG_MAX
    2097152

and if you do hit them, they're very easy to raise:

    $ ulimit -s 32768
    $ getconf ARG_MAX
    8388608

xargs is still useful for its other features, of course.

# echo "2097152/$(echo "/my/still/quite/reasonable/path/to/a/file"|wc -c)"|bc 49932

linux-2.6 # git ls-files|wc -l 36747

Getting close! :)

And I would guesstimate (Linux, kernel >= 2.6.23) to still be a fairly small amount of the machines people interact with professionally through a command line.

And if in a script/snippet, you often want to cover a vast majority of the systems you _could_ end up with. Won't be System III, at least for me, but there has to be a RHEL5 system in a closet right? :)

That's the kernel's limit, Bash (3) has its own limit, which is significantly lower, I've hit it before. I think Bash 4 can do an arbitrary number of arguments, within the kernel's limit.

No, bash doesn't and didn't have its own limit. On an ancient system (Debian Sarge), ARG_MAX=131072:

    $ bash --version
    GNU bash, version 2.05b.0(1)-release (i386-pc-linux-gnu)
    Copyright (C) 2002 Free Software Foundation, Inc.
    $ strace bash -c '/bin/echo `seq 1 30000`' 2>&1 | grep exec
    execve("/bin/bash", ["bash", "-c", "/bin/echo `seq 1 30000`"], …) = 0
    execve("/bin/echo", ["/bin/echo", "1", …) = -1 E2BIG (Argument list too long)

As you can see, the argument list too long error came back from the execve syscall, i.e., from the kernel. (Note that I shortened the strace output to make it fit the page)

Of course, I meant my version as an alternative to xargs. And I think you have about 128k of space for the filenames, but yeah with large projects that can be a problem.

Thanks for the link, that's more interesting than the submission. :)

Fair point, I just submitted it :)

Or maybe, if you have GNU grep:

    $ grep -R --include=\*.py import .