This question may look like a duplicate, but only at first glance.
Of course, I would no longer need help in how to code a one-liner that extracts a fixed number of continuous lines (e. g. 5 in this example) from a data source, e. g. top
:
$ top -b -n1 | awk 'BEGIN {printf "%23s %7s\n","cpu","mem"} NR==8,NR==12 {printf "%-16s %6s%% %6s%%\n",$12,$9,$10}'
This is even a very handy one-liner that will show the processes in the system that take most CPU, with the memory usage being printed in an additional column.
So far, so good ... however, it's not that trivial. To get this list, top
is necessary and may (on low system load) show up itself as process in this list. I'd rather not want that, since these calls are done in intervals and would regularly spawn top
(if only for a short while).
It is known that we want to begin at line 8 (NR==8). However, what if a second top
in another virtual desktop was forgotten about in a terminal which messes up the list as well? In this case, two top
processes must be omitted, so the last line to process will be 14.
So to improve this output and to filter out every top
line that is in there, a counter seems mandatory (perhaps a for
loop that we exit with a break
?).
Unfortunately my attempts with a for loop and i = <number>
have been fruitless so far, because it would rather print every line as many times as i
indicates.
I've come up with a rather hackish solution, which works but may be unsuitable for more complex cases:
top -b -n1 | grep -v ' \btop\b$' | awk 'BEGIN {printf "%23s %7s\n","cpu","mem"} NR==8,NR==12 {printf "%-16s %6s%% %6s%%\n",$12,$9,$10}'
(Note: This may give unwanted results if the user name in the second column happens to be "top" as well)
Anyways, could I get a clue how to do that in awk
please (and get rid of the grep
)?
Thanks in advance.