3 ms·

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 t

by ptramo 15y ago

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.html http://www.dwheeler.com/essays/fixing-unix-linux-filenames.h...

Jach 15y ago
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. :)
- ptramo 15y ago
  Fair point, I just submitted it :)
derobert 15y ago
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.
- ptramo 15y ago
  # 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? :)
- LukeShu 15y ago
  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.
  - derobert 15y ago
    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)

by ptramo 15y ago

Jach 15y ago

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. :)

ptramo 15y ago
Fair point, I just submitted it :)

derobert 15y ago

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.

ptramo 15y ago
# 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? :)
LukeShu 15y ago
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.
- derobert 15y ago
  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)