UNIX for Dummies Questions & Answers

Hi,

What is the maximum number of arguments that could be passed to zsh ?

To find out that I tried a simple script.

And the maximum number of arguments that could be passed turned out to be 23394

Code:

#! /bin/zsh

arg=1

i=1
subIndex=23000
while [ $i -le $subIndex ]
do
  arg=$arg" "$i
  i=$(($i + 1))
done

while :
do
  line="./subTest.zsh "$arg
  echo "$line" | zsh
  i=$(($i + 1))
  arg=$arg" "$i
done

exit 0

Code:

>cat subTest.zsh
#! /bin/zsh

echo "Argument count: ${#}"

exit 1

Am not sure whether this approach is current or not.

Or is the maximum number of arguments that could be passed to a shell stored somewhere ?

Please, shed some light upon this

Hi.

At a quick skim, the article at The maximum length of arguments for a new process looked like it covered most of the bases ... cheers, drl

Thanks for that and I had a chance to look at that link already

To verify the numbers displayed are the maximum number of arguments that could be passed to zsh, I tried the small script posted above

But the numbers turned out to be quite different and wondering why there is a difference in the maximum number of arguments I could pass and to those that is listed.

Any thoughts about this ?

There are two blocks of variable data passed to a new process...

1. environment variables

2. command line arguments

When "exec" is called the kernel has to hold them somewhere while it loads in the new program.

So it may not be the number of arguments, but the length of all the strings plus some management overhead.

Does that mean if the maximum number of arguments that can be passed is 'x' and the number of environmental variables to a binary is 'y', then the "actual" number of arguments that can be passed is only 'x' - 'y'

I believe, each of the command that is typed in the shell has to obey "fork" and "exec" to execute the command


Thanks for the reply

The actual limits/rules is down to the specific operating system.

Yes, exec is the only way a new program gets loaded under UNIX.

Ok.
The its a question about the link posted by drl -- why my script showed different numbers ( as maximum number of arguments possible ) to that of the numbers shown in the link