Using shell command in awk not working

Question

I have the following code in shell.

It does not work. So I don't know what's my mistake I was wondering if someone could help me

echo $i | awk -F "," '{if(NF == 1) print "Exiting..." system("exit")}'

so $i is a parameter for example hi,hello. And if the number of fields is equal to 1, I'd like the program to exit.

Do you want the script that contains the above code to exit? Since the awk command runs in a different process you cannot exit like this. You could however call the exit command (without system) from awk, with a specific exit code, and then check awk's exit code from the shell script. — user000001
– user000001, Commented Oct 21, 2013 at 16:37
@user000001 if NF is equal to 1, I want the WHOLE code to exit. — Matt
– Matt, Commented Oct 21, 2013 at 16:39

tripleee · Accepted Answer · 2013-10-21 16:42:15Z

3

Awk cannot force its parent process to exit, but you can refactor the code so the calling shell exits.

In this limited context, you don't need Awk at all, though.

case $i in
  *,* ) ;; # nothing
  * ) echo Exiting... >&2; exit 1;;
esac

answered Oct 21, 2013 at 16:42

tripleee

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Matt · Accepted Answer · 2013-10-21 17:01:17Z

2

You cannot call exit through system, because awk is executed in a separate process. However, you can call exit from awk, with a specified error code, and then exit the script depending on the error code. Example:

awk -F "," '{if(NF==1){ print "Exiting"; exit -1}}' || exit

edited Oct 21, 2013 at 17:01

Matt

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answered Oct 21, 2013 at 16:44

user000001

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5 Comments

user000001 Over a year ago

@Matin It shouldn't exit for NF>1. Perhaps you did not separate the fields with comma (,)? Also note that you forgot a set of curly brackets in the code in your question

Matt Over a year ago

i do :( I have my string is --only:4,3,2,1 lots of commas. but it still exits

user000001 Over a year ago

@Matin Strange... Try echo "1,2,3 " | awk -F "," '{if(NF==1){ print NF "Exiting"; exit -1}}' || exit. I did it on my system and it worked...

Matt Over a year ago

it worked The problem was <<< "1" I didn't have to put that

user000001 Over a year ago

@Matin Yes the <<< "1" is a different way of specifying input redirection when the input is a string (equivalent to echo "1" | ...) If the input comes from another command, then you should not add it.

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