awk substitute shell variables

Question

I am struggling with awk substitution, for some reason the following code does not substitute anything, it just prints the output unaltered. Can anyone see what I am missing here? Any help would be very much appreachiated! (PS! The $DOCPATH and $SITEPATH are shell variables, they work perfectly fine in my awk setup).

awk -v docpath="$DOCPATH" -v sitepath="$SITEPATH" '{ sub( /docpath/, sitepath ) } { print }'

score 15 · Accepted Answer · answered Dec 17 '13 at 08:58

15

Saying:

sub( /docpath/, sitepath )

causes awk to replace the pattern docpath, not the variable docpath.

You need to say:

awk -v docpath="$DOCPATH" -v sitepath="$SITEPATH" '{sub(docpath, sitepath)}1' filename

answered Dec 17 '13 at 08:58

devnull

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this way is totally wrong way to go, should refer sed command which perreal provided. – BMW Dec 18 '13 at 02:02
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Yeah, my actual script is bit more complex. I need to paste in suffix and prefix stuff as well. Awk therefor works well, but if my problem was isolated to this issue alone I would probably go for the sed solution. Thanks for your helpful feedback :) – Dan-Simon Myrland Jan 17 '14 at 11:13

perreal · Answer 2 · 2013-12-18T03:11:28.653

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Couldn't help to write this in sed:

sed 's/'"$DOCPATH"'/'"$SITEPATH"'/' input

edited Dec 18 '13 at 03:11

answered Dec 17 '13 at 09:01

perreal

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since original awk command used sub(), you should not add g option in sed. – BMW Dec 18 '13 at 02:03
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generally, if the variables (`$SITEPATH`) contain newlines this won't work. – Vassilis Feb 12 '16 at 23:47

score 1 · Answer 3 · answered Dec 17 '13 at 08:58

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/docpath/ will search for the literal string "docpath", not the variable as you want. Just use sub(docpath, sitepath).

N.b. if there could be multiple matches in the same line, you'll want gsub instead of sub.

answered Dec 17 '13 at 08:58

Kevin

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awk substitute shell variables

3 Answers3