bash script assign variable to an associative array

Question

I have been struggling with a new concept to me - associative arrays in a bash script.

Here is simplified version of my code:

#!/bin/bash
declare -A MYID
MYID[hello]=world
tac /home/user/filename | while read -r line; do
  MYID[hello]=me
done
echo "${MYID[hello]}"
exit

This is what I thought it would do: 1) declare an associative array called MYID 2) in MYID assign the value world to the key hello 3) read the file /home/user/filename backwards line by line 4) every time it reads a line assign me to the key hello in the MYID array 5) print out "me" and exit

What it does do is print out "world" instead of "me". What am I doing wrong?

chepner · Accepted Answer · 2013-01-17 19:30:39Z

2

The pipe creates a subshell, so any changes you make to MYID in the while loop only exist in that subshell. Try this instead:

while read -r line; do
    MYID[hello]=me
done < <(tac /home/user/filename)

answered Jan 17, 2013 at 19:30

chepner

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1 Comment

user1464409 Over a year ago

Thank-you, this seems to work. I will add this to my list of things to learn.

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