There are a lot of good old Linux commands to see what’s happening inside your system, with all the power and flexibility you need to zero in on just the information you want. Want to see who is sucking up the most resources on your computer? You can use the good old ps command. This example lists the top 7 hogs, excluding your own processes:
$ ps aux --sort=-%cpu | grep -m 8 -v `whoami` USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 1558 4.1 1.6 193620 68532 tty8 Rs+ 07:05 16:10 /usr/bin/X root 55 0.0 0.0 0 0 ? S 07:05 0:21 [kswapd0] root 7615 0.0 0.0 0 0 ? S 12:06 0:02 [kworker/2:0] root 1772 0.0 0.0 0 0 ? S 07:05 0:10 [flush-8:16] mysql 1262 0.0 4.5 549912 185232 ? Ssl 07:05 0:10 /usr/sbin/mysqld root 9478 0.0 0.0 0 0 ? S 12:54 0:00 [kworker/1:1] root 9832 0.0 0.0 0 0 ? S 13:25 0:00 [kworker/0:1]
You can modify this particular incantation to sort by any ps category, like this example that displays the seven biggest memory users (that are not you):
$ ps aux --sort=-%mem | grep -m 8 -v `whoami` USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND mysql 1262 0.0 4.5 549912 185232 ? Ssl 07:05 0:12 /usr/sbin/mysqld root 1558 4.0 1.7 197268 72352 tty8 Ss+ 07:05 18:10 /usr/bin/X root 1310 0.0 1.3 122728 53032 ? Ss 07:05 0:05 /usr/sbin/spamd root 1329 0.0 1.2 122728 52164 ? S 07:05 0:00 spamd child root 1328 0.0 1.2 122728 52140 ? S 07:05 0:00 spamd child root 3156 0.0 0.2 95320 10204 ? S 08:53 0:00 /usr/bin/python root 1559 0.0 0.2 311480 8156 ? Ss 07:05 0:00 /usr/sbin/apache2 -k start
Or who has been running the longest:
$ ps aux --sort=-time | grep -m 8 -v `whoami` USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 1558 4.0 1.7 197268 72352 tty8 Ss+ 07:05 18:12 /usr/bin/X root 55 0.0 0.0 0 0 ? S 07:05 0:21 [kswapd0] mysql 1262 0.0 4.5 549912 185232 ? Ssl 07:05 0:12 /usr/sbin/mysqld root 1772 0.0 0.0 0 0 ? S 07:05 0:11 [flush-8:16] root 3 0.0 0.0 0 0 ? S 07:05 0:05 [ksoftirqd/0] root 1310 0.0 1.3 122728 53032 ? Ss 07:05 0:05 /usr/sbin/spamd root 845 0.0 0.0 0 0 ? S 07:05 0:03 [jbd2/sdb3-8]
You might have noticed that to get 7 results, you need to use grep -m 8. I shall leave it as your homework to read man grep to learn why.
The ps command has some built-in sorting options. ps aux displays all running processes, and the users they belong to. You can view processes per user with the -U option:
$ ps -U carla
Or multiple users:
$ ps -U postfix -U mysql
Child processes? Piglet processes!
You can see all child processes:
$ ps -eo pid,args --forest [...] 397 /sbin/udevd --daemon 9900 _ /sbin/udevd --daemon 9901 _ /sbin/udevd --daemon 815 upstart-socket-bridge --daemon 881 smbd -F 896 _ smbd -F 884 /usr/sbin/sshd -D [...]
Or all child processes of a particular process:
$ ps -f --ppid 1559 UID PID PPID C STIME TTY TIME CMD www-data 1576 1559 0 07:05 ? 00:00:00 /usr/sbin/apache2 -k start www-data 1577 1559 0 07:05 ? 00:00:00 /usr/sbin/apache2 -k start www-data 1578 1559 0 07:05 ? 00:00:00 /usr/sbin/apache2 -k start www-data 1579 1559 0 07:05 ? 00:00:00 /usr/sbin/apache2 -k start www-data 1580 1559 0 07:05 ? 00:00:00 /usr/sbin/apache2 -k start www-data 9526 1559 0 13:00 ? 00:00:00 /usr/sbin/apache2 -k start
Please read man ps, man sort, and man grep to learn more.
