How to pass AWK output into variable?

Question

I have a small bash script that greps/awk paragraph by using a keyword.

But after adding in the extra codes : set var = "(......)" it only prints a blank line and not the paragraph.

So I would like to ask if anyone knows how to properly pass the awk output into a variable for outputting?

My codes:

#!/bin/sh

set var = "(awk 'BEGIN{RS=ORS="\n\n";FS=OFS="\n"}/FileHeader/' /root/Desktop
/logs/Default.log)"
echo $var;

Thanks!

Make it a habit to always put double quotes around variables: `echo "$var"`. This typically bites users with filenames containing spaces. — glenn jackman, Sep 24 '10 at 17:10

Lesmana · Accepted Answer · 2015-01-30T12:28:12.373

9

Use command substitution to capture the output of a process.

#!/bin/sh

VAR="$(awk 'BEGIN{RS=ORS="\n\n";FS=OFS="\n"}/FileHeader/' /root/Desktop/logs/Default.log)"
echo "$VAR"

some general advice with regards to shell scripting:

(almost) always quote every variable reference.
never put spaces around the equals sign in variable assignment.

edited Jan 30 '15 at 12:28

answered Sep 24 '10 at 05:00

Lesmana

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@JavaNoob, you have to be carefull with backslashes inside the backticks. see here http://mywiki.wooledge.org/BashFAQ/082 – Lesmana Sep 24 '10 at 18:24

score 3 · Answer 2 · edited Apr 24 '11 at 19:16

3

You need to use "command substitution". Place the command inside either backticks, `COMMAND` or, in a pair of parentheses preceded by a dollar sign, $(COMMAND).
To set a variable you don't use set and you can't have spaces before and after the =.

Try this:

var=$(awk 'BEGIN{RS=ORS="\n\n";FS=OFS="\n"}/FileHeader/' /root/Desktop/logs/Default.log)
echo $var

edited Apr 24 '11 at 19:16

glenn jackman

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answered Sep 24 '10 at 07:21

dogbane

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score 2 · Answer 3 · answered Oct 08 '11 at 23:26

2

You gave me the idea of this for killing a process :). Just chromium to whatever process you wanna kill.

Try this:

VAR=$(ps -ef | grep -i chromium | awk '{print $2}'); kill -9 $VAR 2>/dev/null; unset VAR;

answered Oct 08 '11 at 23:26

cokedude

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You generally want to use the `ps -C` argument, as in `ps -C chromium`. Using grep with ps output like this will eventually come back to bite you when there's a filename open in vim or something which matches the command you were grepping for. And you can specify that just the pid be in the output, saving awk by using `ps -C chromium -o pid=`. – dannysauer Feb 11 '16 at 02:52
Or just use `killall chromium`, I guess ;) – dannysauer Feb 11 '16 at 02:53

score 1 · Answer 4 · edited Apr 23 '16 at 16:39

1

anytime you see grep piped to awk, you can drop the grep. for the above,

awk '/^password/ {print $2}'

awk can easily replace any text command like cut, tail, wc, tr etc. and especally multiple greps piped next to each other. i.e

grep some_co.mand | a | grep b ... to | awk '/a|b|and so on/ {some action}.

edited Apr 23 '16 at 16:39

wogsland

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answered Apr 23 '16 at 12:44

jim

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score 0 · Answer 5 · edited Feb 11 '16 at 02:36

0

Try to create a variable coming from vault/Hashicorp, when using packer template variables, like so:

BUILD_PASSWORD=$(vault read secret/buildAccount| grep ^password | awk '{print $2}')
echo $BUILD_PASSWORD

You can to the same with grep ^user

edited Feb 11 '16 at 02:36

Stephan Kristyn

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answered Feb 10 '16 at 17:00

Kenneth King

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How to pass AWK output into variable?

5 Answers5