awk display variable with environment content

Question

I'm getting from system one variable that returns a string, like:

$VARIABLE/dir/text.file

I tryed to use gsub, but I'm missing something:

onstat -c | grep ^MSGPATH | awk 'gsub (/$INFORMIXDIR/, ${INFORMIXDIR}) {print $2}'

It returns error:

awk: cmd. line:1: gsub (/$INFORMIXDIR/, ${INFORMIXDIR}) {print $2}
awk: cmd. line:1:                        ^ syntax error
awk: cmd. line:1: gsub (/$INFORMIXDIR/, ${INFORMIXDIR}) {print $2}
awk: cmd. line:1:                                     ^ 0 is invalid as number of arguments for gsub

What could be the problem?

but do you want to print the variable value inside awk? or what? — Alejandro Teixeira Muñoz, Dec 27 '17 at 16:17
it returns:$INFORMIXDIR/tmp/online.log and I need to use that value after, the INFORMIXDIR is one environment variable. — Sergio Peres, Dec 27 '17 at 16:17
and what you need is to print the environment value for $INFORMIXDIR/tmp/online.log inside AWK, right? — Alejandro Teixeira Muñoz, Dec 27 '17 at 16:18
Possible duplicate of [How do I use shell variables in an awk script?](https://stackoverflow.com/questions/19075671/how-do-i-use-shell-variables-in-an-awk-script) — kvantour, Sep 18 '19 at 14:59

score 2 · Answer 1 · answered Dec 27 '17 at 16:28

2

Because the awk body is in single quotes, you can't expand shell variables. The way to do this safely is to pass the value to awk with the -v option:

... | awk -v dir="$INFORMIXDIR" 'gsub (/\$INFORMIXDIR/, dir) {print $2}'

Note that you have to escape the $ in the regular expression, because it is a special regex character (meaning "end of string")

answered Dec 27 '17 at 16:28

glenn jackman

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Maybe avoid the regex escape and use `[$]` instead – kvantour Sep 18 '19 at 14:57

awk display variable with environment content

1 Answers1