You can use ps to list details of the processes running on your system and awk to filter for a particular program and total the values.
In this case we’ll total the RSS, which is awk’s 6th token hence the $6 in the command. If you wanted to total the %CPU, %MEM, VSZ or any other value provided by ps aux, simply count its column number n and use $n instead.
me@pc ~ $ ps aux | awk '/firefox/ {total+=$6} END {print total}'
965284
One gotcha
When you run the command be aware of which processes are being found by awk. If it’s picking up too many processes then change the /regular expression/ accordingly.
In the example used above, note that the result will include the RSS of the command you just run - because it will match the regexp you’re using - as you can see if you run it without totaling the values:
me@pc ~ $ ps aux | awk '/firefox/'
steph 3993 6.7 20.0 1611068 812984 pts/0 Sl 19:46 14:40 firefox
steph 4039 2.8 3.7 586524 151396 pts/0 Sl 19:47 6:07 /usr/lib64/firefox/plugin-container /opt/Adobe/flash-player/flash-plugin/libflashplayer.so -greomni /usr/lib64/firefox/omni.ja 3993 false plugin
steph 6004 0.0 0.0 10700 900 pts/2 S+ 23:24 0:00 awk /firefox/
I don’t know why the total is 4KB too large. It always seems to be.
