Question

I use two commands to scan for channels:

awk 'BEGIN{while(" w_scan -c PL -x " | getline ) print >> "tmp" }'

awk 'BEGIN{while(" w_scan -I tmp -E 0 -t 3 -F " | getline) print >> "channels" }'

I want to do the same, but with one command. How to simplify to skip writing to tmp?

Thank you for your help.

EDIT:

I tried this command, but it does not work:

awk 'BEGIN { while (" w_scan -c PL -x " | getline ){split($0, tab, RS) system( " w_scan -I \047" tab[1] "\047 -E 0 -t 3 -F " ">>" "channels" )}}'

Result error -> enter link description here

EDIT-1

When I use this script does not work.

run.awk

BEGIN { 
  while (" w_scan -c PL -x " | getline ) {
    split($0, tab, RS) 
    system( " w_scan -I '\047'" tab[1] "'\047' -E 0 -t 3 -F >> channels" )
  }
}

Result error → enter link description here

When I use this script, it works well.

sh script

#!bin/bash
awk 'BEGIN{while(" w_scan -c PL -x " | getline ) print >> "tmp" }'
awk 'BEGIN{while(" w_scan -I tmp -E 0 -t 3 -F " | getline) print >> "channels" }'

Result –> enter link description here

Answer 1

Just stick them both in the BEGIN block:

awk '
  BEGIN {
    while(" w_scan -c PL -x " | getline ) print >> "tmp"
    while(" w_scan -I tmp -E 0 -t 3 -F " | getline) print >> "channels"
  }
'

If you want the whole thing on one line you can separate the commands with semicolon:

awk 'BEGIN { while(" w_scan -c PL -x " | getline ) print >> "tmp"; while(" w_scan -I tmp -E 0 -t 3 -F " | getline) print >> "channels" }'

Edit

You’re accessing tmp in both loops, make sure it’s written before the second loop with close and sync:

run.awk

BEGIN {
  while(" w_scan -c PL -x " | getline ) 
    print >> "tmp"
  close("tmp")
  system("sync")
  while(" w_scan -I tmp -E 0 -t 3 -F " | getline) 
    print >> "channels"
}

Execute with:

awk -f run.awk