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What is the size of command line

Hello!

I want to install all rpms from folder using command:

rpm -i `ls packages`

but my friend said that output from ls command can be very long and it can overflow bash buffers.
What is the size of bash command line?

I do believe you are looking for this:

Code:

$ xargs --show-limits

Your environment variables take up 2762 bytes

POSIX upper limit on argument length (this system): 2092342

POSIX smallest allowable upper limit on argument length (all systems): 4096

Maximum length of command we could actually use: 2089580

Size of command buffer we are actually using: 131072

<ctrl-c>



# or, little less accurate

$ getconf ARG_MAX

2097152



# or, previous command made accurate

$ echo $(( $(getconf ARG_MAX) - $(env | wc -c) ))

2094392

All 3 show the maximum character length of arguments.

It's not a bash limit but you can get the E2BIG error from the execve call.

In any case, the use of ls here is not only unnecessary, but also wrong. The proper way to run the command is with a simple globbing pattern.

Code:

rpm -i *.rpm

If you need to avoid the max argument limit, you can do store the files in an array first, and loop over them.

Code:

rpmarray=( *.rpm )



for (( i=0; i<${#rpmarray[*]}; i+=25 )); do

        rpm -i ${rpmarray[@]:i:25}"

done

This will loop over all the files, processing 25 at a time.

I ran a quick test of the above on the entire content of my /etc directory, and it had no problems.

Do note though that the above relies on several bash extensions, and won't work properly in a posix-only shell. You'll have to use find and/or xargs if that's necessary.

See here for more on shell limits:
I'm getting "Argument list too long". How can I process a large list in chunks?
http://mywiki.wooledge.org/BashFAQ/095