Why do I get "/bin/sh: Argument list too long" when passing quoted arguments?

Igor Chubin picture Igor Chubin · Jul 13, 2012 · Viewed 37k times · Source

How long can be a command line that can be passed to sh -c ''? (in bash and in bourne shell)

The limit is much lower than that from the OS (in case of modern Linux).

For example:

$ /bin/true $(seq 1 100000)
$ /bin/sh -c "/bin/true $(seq 1 100000)"
bash: /bin/sh: Argument list too long

And how could I circumvent this problem?

Update

I want to note that getconf can't help here (because that is not a system limit):

$ seq 1 100000 | wc -c
588895
$ getconf ARG_MAX
2097152

Update #2

Now I've understood what is the point here. That is not a shell limit, that is a system limit but for the length of each argument, not for the entire arglist.

$ /bin/true $(seq 1 100000)
$ /bin/true "$(seq 1 100000)"
bash: /bin/true: Argument list too long

Thank you, CodeGnome, for the explanation.

Answer

Todd A. Jacobs picture Todd A. Jacobs · Jul 13, 2012

TL;DR

A single argument must be shorter than MAX_ARG_STRLEN.

Analysis

According to this link:

And as additional limit since 2.6.23, one argument must not be longer than MAX_ARG_STRLEN (131072). This might become relevant if you generate a long call like "sh -c 'generated with long arguments'".

This is exactly the "problem" identified by the OP. While the number of arguments allowed may be quite large (see getconf ARG_MAX), when you pass a quoted command to /bin/sh the shell interprets the quoted command as a single string. In the OP's example, it is this single string that exceeds the MAX_ARG_STRLEN limit, not the length of the expanded argument list.

Implementation Specific

Argument limits are implementation specific. However, this Linux Journal article suggests several ways to work around them, including increasing system limits. This may not be directly applicable to the OP, but it nonetheless useful in the general case.

Do Something Else

The OP's issue isn't actually a real problem. The question is imposing an arbitrary constraint that doesn't solve a real-world problem.

You can work around this easily enough by using loops. For example, with Bash 4:

for i in {1..100000}; do /bin/sh -c "/bin/true $i"; done

works just fine. It will certainly be slow, since you're spawning a process on each pass through the loop, but it certainly gets around the command-line limit you're experiencing.

Describe Your Real Problem

If a loop doesn't resolve your issue, please update the question to describe the problem you're actually trying to solve using really long argument lists. Exploring arbitrary line-length limits is an academic exercise, and not on-topic for Stack Overflow.