How to reproduce "Too Many open files" error in Shell

user_2410148 0
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Assume that my open file limit is 1024 per process,

Then how to reproduce Too Many open file error in shell script?

#!/bin/bash
a=0
while [ "$a" -lt 10 ]
do
   echo "Welcome $i times"
 a=`expr $a + 1`
   tail -f /dev/null > myfile$a &
done

I tried above, but it opens 10 files in 10 different processes.

ulimit shell linux
1 Answers

You can use ulimit -n to set the maximum number of open files to a low number, and then open up more than that number of files using exec (Remember that file descriptors 0, 1 and 2 are already open at startup):

#!/usr/bin/env bash

ulimit -n 5
exec 3</dev/null
exec 4</dev/null
exec 5</dev/null
exec 6</dev/null

Running this produces:

foo.sh: line 6: /dev/null: Too many open files
foo.sh: line 7: /dev/null: Too many open files
user_99521960
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