for loop with multiline data

Question

I need to create a script with a loop through a list of items. I want to insert a string in the script.

I tried:

for i in "
a
b
c";
do
 echo "test "$i
done

But that only outputs one string:

test a b c

How would I get this?

testa
testb
testc

(a, b and c are just examples for some longer words, which I got from an OpenOffice Calc file)

Where are you getting the abc list from? A file? Typing it directly? Standard input? — jw013, Nov 5, 2012 at 21:41
And how do you plan to access this "clipboard" from the script? Pasting into standard input? Using something like xclip? — jw013, Nov 5, 2012 at 21:57
I understand your question. you want me to improve the question itself... i edited it now — rubo77, Nov 5, 2012 at 22:03

Ignacio Vazquez-Abrams · Accepted Answer · 2012-11-05 21:28:39Z

25

You'd use a while loop instead.

while read i
do
  echo "test$i"
done <<< 'a
b
c'

answered Nov 5, 2012 at 21:28

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3

For the curious, this is called a "here string", which is a variant of "here documents", which use two less-than signs and a delimiter at the end and beginning of the content
– Hanno Fietz
Nov 10, 2015 at 16:50

Add a comment |

Bonsi Scott · Accepted Answer · 2012-11-05 21:29:27Z

23

export a="
a
b
c
"

for i in $a; do echo "test$i";done

answered Nov 5, 2012 at 21:29

Bonsi Scott

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I just wonder, what's the difference to my script? why do you need to put the string in a variable $a first?
– rubo77
Nov 5, 2012 at 22:00
1

this solves it too: for i in $(echo "a b c"); do echo "test$i";done
– rubo77
Nov 5, 2012 at 22:04
2

@rubo77 The difference is the $a is unquoted, meaning that it undergoes word splitting, whereas "a b c" is quoted, so the shell sees it as all one word.
– jw013
Nov 5, 2012 at 22:05
2

Note that it undergoes work splitting and filename generation. Also, the "export" doesn't make sense here. What's wrong with for i in a b c; do echo "test$i"; done?
– Stéphane Chazelas
Nov 5, 2012 at 23:31
2

If the string lines have spaces in between the characters, the for loop may not work as you desire.
– cgseller
Mar 27, 2019 at 19:05

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