Another Awk one-liner

This one-liner printing third word from the lines beginning with "Mem:" (precisely the lines which first word is "Mem:") but adding the serial number before the word.

awk 'BEGIN {a=1} \
{if ( $1 == "Mem:" ) \
  {printf "%4d  %s\n",  a, $3; a++}}' \
free-prefork.log >mem-prefork.log

BTW. This script is to help me to plot a gnuplot graph based on "used memory" number from free command. plot "mem-prefork.log" will do the rest of job. UPDATE Mike Hommey post force me to rethink my scripts and I found easy way to eliminate if clause:

awk 'BEGIN {a=1} \
/^Mem:/  {printf "%4d  %s\n",  a, $3; a++}' \
free-prefork.log >mem-prefork.log