awk accepting variable supplied by dollar sign in cshell

Question

In c shell script, I'm trying to pass bbb to awk sub, but apparently it does not work.

#!/bin/csh
set aaa=a
set bbb=b

#And I'm using it in awk sub

set ccc=`echo $aaa | awk '{sub("a",$bbb); print $0}'`

echo $ccc

But echos empty and dunno why.

Note if I replace $bbb with "b" then it works well.

see http://stackoverflow.com/questions/19075671/how-to-use-shell-variables-in-awk-script — ctrl-alt-delor, Jul 18 '16 at 09:37

score 1 · Accepted Answer · answered Jul 18 '16 at 08:19

1

You have to pass the shell variable to awk. Either with

set ccc=`echo $aaa | awk -v bb=$bbb '{sub("a",bb); print $0}'`

either close and reopen the awk quoting when referring to the shell variable :

set ccc=`echo $aaa | awk '{sub("a",'$bbb'); print $0}'`

answered Jul 18 '16 at 08:19

magor

Explanation: The shell (`csh`, `bash` etc) does not expand variable when in single tick quotes (`'$this_is_not_expanded'`). – ctrl-alt-delor Jul 18 '16 at 09:28

1 Answers1