need help with my bash script

stympman · 10-20-2008, 05:15 PM

In the code below, I am supposed to send singals in. The loop send all output to the /dev/null but when I send the signal in, I need the output from those traps commands to be sent to the screen.

Code:

trap "cd .." 1
trap "pwd; ls -l" 2
trap "ps; sleep 5" 15
i=0
while true
do
      i=`expr $i + 1`
      if [ $i -eq 500 ]
             echo "Hey $USER, I am still runnning"
             THIS LINE WILL GENERATE AN ERROR
             i=o
       fi
done 2> /dev/null > /dev/null &

blacky_5251 · 10-20-2008, 07:09 PM

Looks a lot like homework to me....

I got this to work:-

Code:

#!/bin/bash
trap "cd .." 1
trap "pwd >&2; ls -l >&2" 2
trap "ps >&2; sleep 5" 15
typeset -i i
i=0
while true
do
      i=`expr $i + 1`
      if [ $i -eq 500 ]; then
             echo "Hey $USER, I am still runnning"
             THIS LINE WILL GENERATE AN ERROR
             i=o
      fi
done > /dev/null

I don't understand why you redirected stderr to /dev/null at the end of the while loop, or why you're redirecting stdout for that matter either.

My changes send output from the trap statements to stderr, which I have removed from your redirect syntax at the end of the while loop.