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In bash, I know that it is possible to write a for loop in which some loop control variable i iterates over specified integers. For example, I can write a bash shell script that prints the integers between 1 and 10:

#!/bin/bash

for i in {1..10}
do
 echo $i
done

Is it possible to instead iterate over a loop control variable that is a string, if I provide a list of strings? For example, suppose that I have a string fname that represents a file name. I want to call a set of commands for each file name. For example, I might want to print the contents of fname using a command like this:

#!/bin/bash

for fname in {"a.txt", "b.txt", "c.txt"}
do
 echo $fname
done

In other words, on the first iteration, fname should have the value fname="a.txt", while on the second iteration, fname should have the value fname="b.txt", and so on. Unfortunately, it seems that the above syntax is not quite correct. I would like to obtain the output:

a.txt

b.txt

c.txt

but when I try the above code, I obtain this output:

{a.txt,

b.txt,

c.txt}

Can you please help me determine the correct syntax, so that I can iteratively change the value/contents of the variable fname? Thank you for your time.

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2  
Remove the {}, you don't need anything to loop over a (space-delimited) list –  Mat Sep 8 '12 at 15:54
2  
@Mat means remove the {} and the ,s. The alternative is to remove the spaces. So either "a.txt" "b.txt" "c.txt" or {"a.txt","b.txt","c.txt"}. But I prefer {a..c}.txt instead. –  manatwork Sep 8 '12 at 16:20
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1 Answer

up vote 6 down vote accepted

The correct syntax is as follows:

#!/bin/bash

for fname in a.txt b.txt c.txt
do
  echo $fname
done
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3  
Also, assuming an array of names fnames=( a.txt b.txt c.txt ) you can use the syntax for f in ${fnames[@]}; do echo $f; done. –  Herman Torjussen Sep 8 '12 at 19:12
    
Is it true that for fname in a.txt b.txt c.txt and for fname in "a.txt" "b.txt" "c.txt" yield identical results? –  Andrew Sep 8 '12 at 19:39
    
Andrew, yes it is true. They will yield identical results –  Ali Gangji Sep 8 '12 at 20:29
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