Linux commands to display the system processes information
ps command
godarda@gd:~$ ps
PID TTY TIME CMD
3368 pts/0 00:00:00 bash
3372 pts/0 00:00:00 ps
godarda@gd:~$ ps -a
PID TTY TIME CMD
2377 tty2 00:00:08 Xorg
2417 tty2 00:00:00 gnome-session-b
3373 pts/0 00:00:00 ps
godarda@gd:~$ ps -aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.5 0.1 167952 11684 ? Ss 18:24 0:01 /sbin/init sp
root 2 0.0 0.0 0 0 ? S 18:24 0:00 [kthreadd]
root 3 0.0 0.0 0 0 ? I< 18:24 0:00 [rcu_gp]
root 4 0.0 0.0 0 0 ? I< 18:24 0:00 [rcu_par_gp]
root 5 0.3 0.0 0 0 ? I 18:24 0:01 [kworker/0:0-
root 6 0.0 0.0 0 0 ? I< 18:24 0:00 [kworker/0:0H
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root 3380 0.0 0.0 24724 5840 ? S 18:30 0:00 /lib/systemd/
root 3579 0.0 0.0 9492 3348 ? S 18:30 0:00 /bin/bash /et
root 3585 0.0 0.0 8272 776 ? S 18:30 0:00 flock --nonbl
root 3586 4.5 0.0 8168 2328 ? DN 18:30 0:00 /usr/bin/upda
kodingw+ 3587 0.0 0.0 11888 3724 pts/0 R+ 18:30 0:00 ps -aux
godarda@gd:~$
Extract specific columns
godarda@gd:~$ ps -e
PID TTY TIME CMD
1 ? 00:00:02 systemd
2 ? 00:00:00 kthreadd
3 ? 00:00:00 rcu_gp
4 ? 00:00:00 rcu_par_gp
5 ? 00:00:01 kworker/0:0-events
6 ? 00:00:00 kworker/0:0H-kblockd
8 ? 00:00:01 kworker/u8:0-events_unbound
9 ? 00:00:00 mm_percpu_wq
10 ? 00:00:00 ksoftirqd/0
godarda@gd:~$ ps -eo pid,ppid,ni
PID PPID NI
1 0 0
2 0 0
3 2 -20
4 2 -20
5 2 0
6 2 -20
8 2 0
9 2 -20
Sort processes based on column attributes
godarda@gd:~$ ps aux --sort user USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND avahi 949 0.0 0.0 8808 3676 ? Ss 18:25 0:00 avahi-daemon: avahi 1003 0.0 0.0 8544 356 ? S 18:25 0:00 avahi-daemon: kodingw+ 2286 0.0 0.1 19472 10760 ? Ss 18:26 0:00 /lib/systemd/ kodingw+ 2287 0.0 0.0 169324 3816 ? S 18:26 0:00 (sd-pam) kodingw+ 2300 0.0 0.2 2268840 19676 ? S<sl 18:27 0:00 /usr/bin/puls kodingw+ 2302 0.0 0.3 511384 24320 ? SNsl 18:27 0:00 /usr/libexec/ kodingw+ 2305 0.0 0.0 8452 5624 ? Ss 18:27 0:00 /usr/bin/dbus kodingw+ 2310 0.0 0.0 240184 7716 ? Sl 18:27 0:00 /usr/bin/gnom kodingw+ 2325 0.0 0.0 239696 7820 ? Ssl 18:27 0:00 /usr/libexec/
Extract specific process
godarda@gd:~$ ps -aux | grep mysql mysql 1172 1.1 4.4 2120856 352952 ? Ssl 18:25 0:04 /usr/sbin/mysqld kodingw+ 3607 0.0 0.0 8900 724 pts/0 S+ 18:32 0:00 grep mysql godarda@gd:~$ pgrep mysql 1172 godarda@gd:~$ pgrep -l mysql 1172 mysqld godarda@gd:~$ ps -lp 1172 F S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD 4 S 122 1172 1 1 80 0 - 530214 - ? 00:00:10 mysqld
Assign and change the process priority
godarda@gd:~$ su Password: root@gd:/home/godarda# ps -l F S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD 4 S 0 4426 4424 0 80 0 - 2875 do_wai pts/0 00:00:00 su 4 S 0 4427 4426 0 80 0 - 2546 do_wai pts/0 00:00:00 bash 4 R 0 4440 4427 0 80 0 - 2849 - pts/0 00:00:00 ps root@gd:/home/godarda# nice 0 root@gd:/home/godarda# nice -n 5 bash root@gd:/home/godarda# ps -l F S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD 4 S 0 4426 4424 0 80 0 - 2875 do_wai pts/0 00:00:00 su 4 S 0 4427 4426 0 80 0 - 2546 do_wai pts/0 00:00:00 bash 0 S 0 4442 4427 0 85 5 - 2545 do_wai pts/0 00:00:00 bash 4 R 0 4453 4442 0 85 5 - 2849 - pts/0 00:00:00 ps root@gd:/home/godarda# renice -0 4442 4442 (process ID) old priority 5, new priority 0 root@gd:/home/godarda# ps -l F S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD 4 S 0 4426 4424 0 80 0 - 2875 do_wai pts/0 00:00:00 su 4 S 0 4427 4426 0 80 0 - 2546 do_wai pts/0 00:00:00 bash 0 S 0 4442 4427 0 80 0 - 2545 do_wai pts/0 00:00:00 bash 4 R 0 4455 4442 0 80 0 - 2849 - pts/0 00:00:00 ps root@gd:/home/godarda# renice -21 4442 4442 (process ID) old priority 0, new priority -20 root@gd:/home/godarda# ps -l F S UID PID PPID C PRI NI ADDR SZ WCHAN TTY TIME CMD 4 S 0 4426 4424 0 80 0 - 2875 do_wai pts/0 00:00:00 su 4 S 0 4427 4426 0 80 0 - 2546 do_wai pts/0 00:00:00 bash 0 S 0 4442 4427 0 60 -20 - 2545 do_wai pts/0 00:00:00 bash 4 R 0 4476 4442 0 60 -20 - 2849 - pts/0 00:00:00 ps root@gd:/home/godarda#
pstree command
godarda@gd:~$ pstree
systemd─┬─ModemManager───2*[{ModemManager}]
├─NetworkManager───2*[{NetworkManager}]
├─accounts-daemon───2*[{accounts-daemon}]
├─acpid
├─avahi-daemon───avahi-daemon
├─bluetoothd
├─colord───2*[{colord}]
├─cron
├─cups-browsed───2*[{cups-browsed}]
├─cupsd
├─dbus-daemon
├─gdm3─┬─gdm-session-wor─┬─gdm-x-session─┬─Xorg───13*[{Xorg}]
│ │ │ ├─gnome-session-b─┬─ssh-agent
│ │ │ │ └─2*[{gnome-+
│ │ │ └─2*[{gdm-x-session}]
│ │ └─2*[{gdm-session-wor}]
│ └─2*[{gdm3}]
├─geoclue───2*[{geoclue}]
├─gnome-keyring-d───3*[{gnome-keyring-d}]
├─ibus-daemon─┬─ibus-dconf───3*[{ibus-dconf}]
│ ├─ibus-engine-sim───2*[{ibus-engine-sim}]
│ ├─ibus-extension-───3*[{ibus-extension-}]
│ ├─ibus-ui-gtk3───3*[{ibus-ui-gtk3}]
...
top command
godarda@gd:~$ top
top - 18:38:14 up 13 min, 1 user, load average: 0.63, 0.87, 0.87
Tasks: 224 total, 1 running, 223 sleeping, 0 stopped, 0 zombie
%Cpu(s): 4.7 us, 2.0 sy, 0.0 ni, 93.1 id, 0.0 wa, 0.0 hi, 0.2 si, 0.0 st
MiB Mem : 7744.8 total, 4550.7 free, 1583.5 used, 1610.6 buff/cache
MiB Swap: 3815.0 total, 3815.0 free, 0.0 used. 5675.2 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
3099 kodingw+ 20 0 2987604 367320 170248 S 8.0 4.6 0:40.19 MainThr+
2377 kodingw+ 20 0 1143856 87276 54980 S 7.0 1.1 0:32.62 Xorg
2629 kodingw+ 20 0 4488208 257140 101068 S 6.0 3.2 0:40.69 gnome-s+
3357 kodingw+ 20 0 962192 51452 39424 S 3.0 0.6 0:08.14 gnome-t+
3296 kodingw+ 20 0 2684072 250256 153392 S 2.0 3.2 0:18.56 Web Con+
433 root -51 0 0 0 0 S 1.0 0.0 0:02.03 irq/87-+
1 root 20 0 167952 11684 8228 S 0.7 0.1 0:02.50 systemd
1172 mysql 20 0 2120856 352952 33540 S 0.7 4.5 0:08.17 mysqld
2506 kodingw+ 20 0 311420 7728 6056 S 0.7 0.1 0:03.57 ibus-da+
3737 kodingw+ 20 0 12168 4240 3444 R 0.7 0.1 0:00.14 top
8 root 20 0 0 0 0 I 0.3 0.0 0:01.17 kworker+
2515 kodingw+ 20 0 674584 58852 39052 S 0.3 0.7 0:01.86 ibus-ex+
2592 kodingw+ 20 0 162684 7048 6412 S 0.3 0.1 0:00.99 ibus-en+
3203 kodingw+ 20 0 2765492 248912 139908 S 0.3 3.1 1:08.42 Web Con+
3610 root 20 0 0 0 0 I 0.3 0.0 0:00.56 kworker+
2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd
3 root 0 -20 0 0 0 I 0.0 0.0 0:00.00 rcu_gp
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Bash Shell Scripting