awk getline

Shell Programming and Scripting
1

Hi,

I have an awk script with the following function in it .

 function cmd( c )
        {
        
        
                while( ( c | getline foo) > 0 ){
                         return foo ;
                          close( c );

                         }

        }

c = date "+%d" -d "3/6/17 16:26:35 GMT-03:30";

I'm basically trying to convert a given time to system localtime and return back the value to awk.
The script works fine, but if I call the function multiples times I get no return from the function. I'm not sure why, any tip will be appreciated.

Thanks

2

well your close(c) is unreachable and you hit return foo FIRST. And you probably run out of max open file descriptors of awk - depending your version of awk it might be 5 (for AIX, if I recall).

I'd change this to:

function cmd(c,   foo )
{
  while( ( c | getline foo) > 0 ){
    close( c )
    return foo
  }
}
3

In addition to the point vgersh99 makes, since the function will only return one line anyway, and the foo variable is now a local variable which gets initialized as empty, you might as well skip while loop and test :

function cmd(c,   foo){
  c | getline foo
  close( c )
  return foo
}

For multi-line output the while loop would not function anyway.

4

Hi Scrutinizer,
The point of the loop in this code seems to be to return data from the last line of text produced by the command named by c . Without the loop, the function returns the first line of text produced instead of the last. Neither form gathers more than one line of output.

5

Thanks for the tips.

I got it to work as follow

function cmd(c,   foo){
 close( c )
system("") 

(c | getline foo)    
  return foo 
}