Assigning system command's output to variable

awk pipe
Sahas picture Sahas · Dec 25, 2009 · Viewed 83.5k times · Source

I want to run the system command in an awk script and get its output stored in a variable. I've been trying to do this, but the command's output always goes to the shell and I'm not able to capture it. Any ideas on how this can be done?

Example:

$ date | awk --field-separator=! {$1 = system("strip $1"); /*more processing*/}

Should call the strip system command and instead of sending the output to the shell, should assign the output back to $1 for more processing. Rignt now, it's sending output to shell and assigning the command's retcode to $1.

Answer

ghostdog74 picture ghostdog74 · Dec 25, 2009

Note: Coprocess is GNU awk specific. Anyway another alternative is using getline

cmd = "strip "$1
while ( ( cmd | getline result ) > 0 ) {
  print  result
} 
close(cmd)

Calling close(cmd) will prevent awk to throw this error after a number of calls :

fatal: cannot open pipe `…' (Too many open files)

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