Saturday, 26 Jan, 2013

Top is an historic monitoring tool to get a fast overview of a running Linux system. It is especially useful when you're at limited linux consoles and terminals (i.e.: busybox and the like).

By default it doesn't look so great, but there's always fast ways to customize it and use it fruitfully.

Custom top Color Scheme.

Edit ~/.toprc, paste the following then Save:

RCfile for "top with windows"           # shameless braggin'
Id:a, Mode_altscr=0, Mode_irixps=1, Delay_time=3.000, Curwin=0
Def     fieldscur=AEHIOQTWKNMbcdfgjplrsuvyzX
        winflags=63800, sortindx=10, maxtasks=0
        summclr=2, msgsclr=1, headclr=3, taskclr=1
Job     fieldscur=ABcefgjlrstuvyzMKNHIWOPQDX
        winflags=62777, sortindx=0, maxtasks=0
        summclr=6, msgsclr=6, headclr=7, taskclr=6
Mem     fieldscur=ANOPQRSTUVbcdefgjlmyzWHIKX
        winflags=62777, sortindx=13, maxtasks=0
        summclr=5, msgsclr=5, headclr=4, taskclr=5
Usr     fieldscur=ABDECGfhijlopqrstuvyzMKNWX
        winflags=62777, sortindx=4, maxtasks=0
        summclr=3, msgsclr=3, headclr=2, taskclr=3

top running with the previous color scheme applied to it (green|white|red is not casual):

how top looks on a pwrusr linux server, by editing its ~/.toprc file as described above.

My favourite top options.

Some of my top tricks...

top -cSb n 1 > running.log

Shows you the full top text output, very useful to take a snapshot of a running system to analyze afterwards. Please note the output of the previous command is very similar to the ps command.

top -cSb n 1 -p PID

Useful to monitor a process (check also my fav ps options to know how to get the PID of a daemon).

top -cSb -p PID n 1 | tail -n+8 | sort -rn -k5 | awk 'NR > 0 { s +=$9 }; END {print "cpu %",s}'

To monitor the CPU usage (in percent) of a single process, identified by a PID, with top.

What's the difference between the previous 2 commands? Check this screenshot:

one gives you the full top header output, the other only the cpu usage.

As you can see by the previous screenshot, the two commands above differ by the full top header output.

The second one is very useful on bash scripts.

Also, some of the previous commands are extremely useful when used in conjunction with the watch command.

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