Why does this for-loop not process all elements of the array?

Question

Given the following script:

#!/bin/bash

asteriskFiles=("sip.conf" "extensions.conf")

for asteriskFile in $asteriskFiles
do
    # backup current configuration file
    cp somepath/${asteriskFile} test/
    echo "test"
done

This gives me the output "test" only once, so the loop runs only once instead of two times (two entries in asteriskFiles array). What am I doing wrong? Thanks for any hint!

kojiro · Accepted Answer · 2012-07-09 19:24:08Z

11

An illustration:

$ asteriskFiles=("sip.conf" "extensions.conf")
$ echo $asteriskFiles # is equivalent to echo ${asteriskFiles[0]}
sip.conf
$ echo "${asteriskFiles[@]}"
sip.conf extensions.conf

Note that the quotes are important. echo ${asteriskFiles[@]} might seem to work, but bash would wordsplit on whitespace if any of your files had whitespace in them.

answered Jul 9, 2012 at 19:24

kojiro

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2 Comments

Tim Pote Over a year ago

+1 for a great explanation of the problem without spoon-feeding the final answer.

me.at.coding Over a year ago

I had to look at the answer twice, but I understand, thank you very much! So by default $array maps to the first element and not the whole array. Strange syntax with the [@] for me though. Anyway, it works and I know it now ;-)

Rucent88 · Accepted Answer · 2012-07-09 19:31:51Z

2

Write the beginning of your loop like this

for asteriskFile in "${asteriskFiles[@]}"

answered Jul 9, 2012 at 19:31

Rucent88

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Comments

Todd A. Jacobs · Accepted Answer · 2012-07-09 19:31:54Z

2

The Probem

The asteriskFiles variable holds an array. If you dereference it like a scalar, you only get the first element of the array.

The Solution

You want to use the correct shell parameter expansion to access all the subscript elements. For example:

$ echo "${asteriskFiles[@]}"
sip.conf extensions.conf

The @ subscript (when correctly quoted) will expand to the properly-tokenized elements of your array, which your for-loop will then be able to iterate over.

answered Jul 9, 2012 at 19:31

Todd A. Jacobs

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