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Array output through a for loop problematic with multiple elements.

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Top Forums Shell Programming and Scripting Array output through a for loop problematic with multiple elements.
# 8  
Old 10-01-2011
Quote:
Originally Posted by Azrael
That works perfect until I try to output it from my array. (Which I dearly need).

Code:
#!/bin/bash

if [ 5.21 = $(nmap --version | awk '/Nmap/ { print $3 }') ]; then
    i=5  t=report    # field index and target text
else
    i=2  t=Host
fi

/sbin/ifconfig | awk '/inet addr/ && !/127.0.0.1/ && !a[$2]++ {print substr($2,6)}' |
    while read ip; do
          first+=( "$(nmap -sP ${ip%.*}.0/24 | awk 'index($0,t) { print $i }' t="$t" i="$i" )" )
          sleep 1
    done

echo "${first[@]}"

The above outputs absolutely nothing. Don't bother running it.
That's happening because bash runs the highlighted while-loop portion of the pipeline in a subshell. Any modification to $first, in that subshell, is not visible in the parent shell (where the echo happens).

Perhaps the third time is indeed the charm? Smilie:
Code:
#!/bin/bash

if [ 5.21 = $(nmap --version | awk '/Nmap/ { print $3 }') ]; then
    i=5  t=report    # field index and target text
else
    i=2  t=Host
fi

for ip in $(/sbin/ifconfig | awk '/inet addr/ && !/127.0.0.1/ && !a[$2]++ {print substr($2,6)}')
do
          first+=( "$(nmap -sP ${ip%.*}.0/24 | awk 'index($0,t) { print $i }' t="$t" i="$i" )" )
          sleep 1
done

echo "${first[@]}"

Regards,
Alister
Last edited by alister; 10-01-2011 at 12:06 PM..
This User Gave Thanks to alister For This Post:
Azrael
# 9  
Old 10-02-2011
Yes! That did the trick! This helped me more than you'll know. Thank you very much!
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