How To Find and Overcome Shell Command Line Length Limitations

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While using mv or rm command I get command line length error (Argument list too long error). How do I find out current running shell command line length limitations? How do I overcomes these limitations while writing UNIX / BSD / Linux shell utilities?

All shell have / has a limit for the command line length. UNIX / Linux / BSD system has a limit on how many bytes can be used for the command line argument and environment variables. When you start a new process or type a command these limitations are applied and you will see an error message as follows on screen:

Argument list too long

How do I find out current command line length limitations?

Type the following command (works under Linux / UNIX / BSD operating systems):
$ getconf ARG_MAX
Sample output:

262144

BSD operating system also supports following command:
$ sysctl kern.argmax
Sample output:

kern.argmax=262144

To get accurate picture about limitation type the following command (hat tip to Jeff):
$ echo $(( $(getconf ARG_MAX) - $(env | wc -c) ))
Output:

261129

How do overcome shell command line length?

You have following option to get around these limitations:

  • Use find or xargs command
  • Use shell for / while loop

find command example to get rid of “argument list too long” error

$ find /nas/data/accounting/ -type f -exec ls -l {} \;
$ find /nas/data/accounting/ -type f -exec /bin/rm -f {} \;

xargs command example to get rid of “argument list too long” error

$ echo /nas/data/accounting/* | xargs ls -l
$ echo /nas/data/accounting/* | xargs /bin/rm -f

while loop example to get rid of “argument list too long” error

ls -1 /nas/data/accounting/ | while read file; do mv /nas/data/accounting/$file /local/disk/ ; done

Alternatively, you can combine above methods:

find /nas/data/accounting/ -type f | 
   while read file
   do
     mv /nas/data/accounting/$file /local/disk/
   done

time command – give resource usage

Use time command to find out exact system resource usage for each command:
$ time find blah blah
$ time ls -1 blah | while read file; do #blah on $file; done

Further readings:

  • Your shell documentation
  • man pages ksh, bash, getconf, sysconf, sysctl, find, and xargs

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

9 comment

  1. When using ‘+’ as end for find(1), you emulate xargs behavior, in that it will only pass the arguments to the command when the argument list is saturated, getting rid of numerous forks.

  2. Hi, thanks for your post. But I guess the “echo * | xargs cmd” would fail because the asterisk will be replaced with all file names and then the echo command will be faced with an “argument list too long” error. Again the find command helps: find -type f | xargs rm -f
    :)

  3. Another way of staying under the limit is to use your resources wisely. Don’t forget that “$ /bin/rm /nas/data/accounting/*” will, after globbing, prepend every filename with “/nas/data/accounting/”, wasting 21 characters per filename, dramatically increasing the length of your command line. Instead, “$ pushd /nas/data/accounting/; /bin/rm *; popd”. Also, I cannot stress enough how important it is to actually test your examples. In addition to the problem with your xargs example, neither of the while loop samples will work, because you specified “/nas/data/accounting” in both the find/ls and the rm. This will duplicate the path in the rm and cause the rm to fail, if you’re lucky. If you’re unlucky it will succeed, and delete the wrong file.

  4. For the common case, GNU `find` (but not BSD `find`) also offers a `-delete` parameter/command. So your

    $ find /nas/data/accounting/ -type f -exec /bin/rm -f {} \;

    example can become

    $ find /nas/data/accounting/ -type f -delete

  5. I think most OS are limited to that number unless the software you are using can go around that. I’ve been using GS RichCopy 360 in dealing with long path file errors and it works very well. Any other suggestions that can be tested out?

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