How to pass values between awk and shell scripts

rajnikanth.1912 · #1 (**permalink**) 10-30-2006

I know that we can call system command to execute shell script in awk.

but it does not return the result of the command executed , but only returns
the value of the command executoin status ( 1/0 --> failure / success).

Could anyone let me know how to solve this problem.

anbu23 · #2 (**permalink**) 10-30-2006

check this
http://www.unix.com/showthread.php?p...#post302094516

kwachtler · #3 (**permalink**) 10-30-2006

Below example will execute a shell command, and ...
1. Read cmd output into current line.
2. Read cmd output into awk variable.

1.
"shell cmd" | getline
2.
"shell cmd" | getline var

Good Luck !
KW

islegmar · #4 (**permalink**) 03-19-2009

Hi,

I have the same problem and I the solutions posted here don't work for me or I don't understand them :-( So, how can I retrive in awk the returned value by a shell command and not its return status (0,1)?

My problem: I want to perform some date manipulation inside awk. For this, I want to convert the dates in the number of seconds using the date shelll command.

cmd=sprintf("date -d %s +%%s",d1);
val=system(cmd);

The problem is that val receives 0 (success) and not the number of seconds.

Thanks a lot

Isi

vgersh99 · #5 (**permalink**) 03-19-2009

As described in this thread....

Code:

system(cmd) | getline val
close(cmd)

islegmar · #6 (**permalink**) 03-19-2009

Hi

Thanks for the reply but I get an error when using getline. Is getline an standard UNIX command (I'm using cygwin :-()? Can I use it inside an awk code?

My code is

Code:

awk -v inicio=$f1 -v fin=$f2 '
function compareDate(d1,d2)
{

  cmd=sprintf("date -d %s +%%s",d1);
  system(cmd)|getline s1;
  close(cmd);
  cmd=sprintf("date -d %s +%%s",d2);
  system(cmd)|getline s2;
  close(cmd);

  if (s1 > s2)
  {
    retVal=1;
  }
  else if ( s1=s2 )
  {
    retVal=0;
  }
  else
  {
    retVal=-1;
  }


  return retVal;
}

doprint==0 && compareDate($1,inicio)>=0 { doprint=1; }
doprint==1 && compareDate($1,fin)>=0    { exit; }
doprint==1 { print;  }

When I execute it, s1 and s2 are always empty and what I see in stdout is the ouput of the 'date' commands

Thanks a lot again

Isi

vgersh99 · #7 (**permalink**) 03-19-2009

Code:

sprintf("date -d %s +%%s",d1)

This actually expects TWO parameters passed to it - you're just passing ONE (d1). Where's the second?
Do you get anything spilled to stderr complaining about 'sprintf'?
What's this '+%%s' supposed to be?

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