I am trying to have a terminal showing the last 5 processes opened. This is helpful for my debugging.
At this point I have
watch ps -ef --sort=start_time
This works fine but it shows all processes so they don't fit in the screen. How can I limit it to a specific number like 5 or 10?
-- Update --
A have tried
watch "ps -ef --sort=start_time | tail -n 5"
but the problem is that the header of ps is omitted so after a while I don't know what I am looking at.
You want:
watch "ps -ef --sort=start_time | tail -n 5"
tail will only output the last n lines piped to it.
I assume you tried:
watch ps -ef --sort=start_time | tail -n 5
Which would try and pipe the output of watch to tail, rather than the output of ps, and as watch never terminates, tail can't determine when the last n lines are output, so also prints nothing.
If you wish to keep the header as well, you can use some clever bash to simply:
watch "ps -ef --sort=start_time | (head -n 1 ; tail -n 5)"
Which causes head to print the top line as well.
watch "ps -f --sort=start_time | (head -n 1 ; tail -n 5)" to see what I mean). To make sure that both programs see all the output, you need to use a temporary file, eg watch "ps -ef --sort=start_time >TempFile; head -n 1 <TempFile ; tail -n 5 <TempFile" (you could also use tee to create tempFile). Both -f and -ef now show the last five lines.
watch ps -ef --sort=start_time | head -5orwatch ps -ef --sort=start_time | tail -5depending on whether the sort is ascending or not