Which command is used to view all running processes on Redhat Linux box?
As we all know Linux is a multitasking and multi-user systems. So, it allows multiple processes to operate simultaneously without interfering with each other. Process is one of the important fundamental concept of the Linux OS. A process is an executing instance of a program and carry out different tasks within the operating system. Show Linux provides us a utility called ps for viewing information related with the processes on a system which stands as abbreviation for “Process Status”. ps command is used to list the currently running processes and their PIDs along with some other information depends on different options. It reads the process information from the virtual files in /proc file-system. /proc contains virtual files, this is the reason it’s referred as a virtual file system. ps provides numerous options for manipulating the output according to our need. Syntax
– ps [options] Options for ps Command :
[root@rhel7 ~]# ps PID TTY TIME CMD 12330 pts/0 00:00:00 bash 21621 pts/0 00:00:00 ps
[root@rhel7 ~]# ps -A [root@rhel7 ~]# ps -e
[root@rhel7 ~]# ps -a PID TTY TIME CMD 27011 pts/0 00:00:00 man 27016 pts/0 00:00:00 less 27499 pts/1 00:00:00 ps Note – You may be thinking that what is session leader? A unique session is assign to every process group. So, session leader is a process which kicks off other processes. The process ID of first process of any session is similar as the session ID.
[root@rhel7 ~]# ps -d
[root@rhel7 ~]# ps -a -N OR [root@rhel7 ~]# ps -a --deselect
[root@rhel7 ~]# ps -T
[root@rhel7 ~]# ps -r
[root@rhel7 ~]# ps -x Process selection by list Here we will discuss how to get the specific processes list with the help of ps command. These options accept a single argument in the form of a blank-separated or comma-separated list. They can be used multiple times.
Syntax : ps -C command_name Example : [root@rhel7 ~]# ps -C dhclient PID TTY TIME CMD 19805 ? 00:00:00 dhclient
Syntax : ps -G group_name ps --Group group_name Example : [root@rhel7 ~]# ps -G root
Syntax : ps -g group_id ps -group group_id Example : [root@rhel7 ~]# ps -g 1 PID TTY TIME CMD 1 ? 00:00:13 systemd
Syntax : ps p process_id ps -p process_id ps --pid process_id Example : [root@rhel7 ~]# ps p 27223 PID TTY STAT TIME COMMAND 27223 ? Ss 0:01 sshd: root@pts/2 [root@rhel7 ~]# ps -p 27223 PID TTY TIME CMD 27223 ? 00:00:01 sshd [root@rhel7 ~]# ps --pid 27223 PID TTY TIME CMD 27223 ? 00:00:01 sshd You can view multiple processes by specifying multiple process IDs separated by
blank or comma – [root@rhel7 ~]# ps -p 1 904 27223 PID TTY STAT TIME COMMAND 1 ? Ss 0:13 /usr/lib/systemd/systemd --switched-root --system --d 904 tty1 Ssl+ 1:02 /usr/bin/X -core -noreset :0 -seat seat0 -auth /var/r 27223 ? Ss 0:01 sshd: root@pts/2
[root@rhel7 ~]# ps -p 766 PID TTY TIME CMD 766 ? 00:00:06 NetworkManager [root@rhel7 ~]# ps --ppid 766 PID TTY TIME CMD 19805 ? 00:00:00 dhclient In above example process ID 766 is assigned to NetworkManager and this is the parent process for dhclient with process ID
19805.
Syntax : ps -s session_id ps --sid session_id Example : [root@rhel7 ~]# ps -s 1248 PID TTY TIME CMD 1248 ? 00:00:00 dbus-daemon 1276 ? 00:00:00 dconf-service 1302 ? 00:00:00 gvfsd 1310 ? 00:00:00 gvfsd-fuse 1369 ? 00:00:00 gvfs-udisks2-vo 1400 ? 00:00:00 gvfsd-trash 1418 ? 00:00:00 gvfs-mtp-volume 1432 ? 00:00:00 gvfs-gphoto2-vo 1437 ? 00:00:00 gvfs-afc-volume 1447 ? 00:00:00 wnck-applet 1453 ? 00:00:00 notification-ar 1454 ? 00:00:02 clock-applet
Syntax : ps t tty ps -t tty ps --tty tty Example : [root@rhel7 ~]# ps -t pts/0 PID TTY TIME CMD 31199 pts/0 00:00:00 bash 31275 pts/0 00:00:00 man 31280 pts/0 00:00:00 less
[tux@rhel7 ~]$ ps -af tux 17327 17326 0 12:42 pts/0 00:00:00 -bash tux 17918 17327 0 12:50 pts/0 00:00:00 ps -af
[tux@rhel7 ~]$ ps -F UID PID PPID C SZ RSS PSR STIME TTY TIME CMD tux 17327 17326 0 28848 2040 0 12:42 pts/0 00:00:00 -bash tux 17942 17327 0 37766 1784 0 12:50 pts/0 00:00:00 ps -F
Syntax : [root@rhel7 ~]# ps --format column_name [root@rhel7 ~]# ps -o column_name [root@rhel7 ~]# ps o column_name Example : [root@rhel7 ~]# ps -aN --format cmd,pid,user,ppid CMD PID USER PPID /usr/lib/systemd/systemd -- 1 root 0 [kthreadd] 2 root 0 [ksoftirqd/0] 3 root 2 [kworker/0:0H] 5 root 2 [migration/0] 7 root 2 [rcu_bh] 8 root 2 [rcu_sched] 9 root 2 [watchdog/0] 10 root 2
[root@rhel7 ~]# ps -j PID PGID SID TTY TIME CMD 16373 16373 16373 pts/0 00:00:00 bash 19734 19734 16373 pts/0 00:00:00 ps
[root@rhel7 ~]# ps l F UID PID PPID PRI NI VSZ RSS WCHAN STAT TTY TIME COMMAND 4 0 904 826 20 0 306560 51456 ep_pol Ssl+ tty1 1:32 /usr/bin/X -core -noreset :0 -seat seat0 -auth /var/run/lightdm/root/:0 -noli 4 0 11692 11680 20 0 115524 2132 do_wai Ss pts/2 0:00 -bash
[root@rhel7 ~]# ps -aM LABEL PID TTY TIME CMD unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 19534 pts/2 00:00:00 man unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 19543 pts/2 00:00:00 less unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 20469 pts/0 00:00:00 ps
[root@rhel7 ~]# ps s 766
[root@rhel7 ~]# ps u 1 USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 1 0.0 0.6 128168 6844 ? Ss Apr08 0:16 /usr/lib/systemd/systemd --switched-root --system --deserialize 21
[root@rhel7 ~]# ps v 1 PID TTY STAT TIME MAJFL TRS DRS RSS %MEM COMMAND 1 ? Ss 0:16 62 1317 126850 6844 0.6 /usr/lib/systemd/systemd --switched-root --system --deserialize 21
[root@rhel7 ~]# ps ev 766 PID TTY STAT TIME MAJFL TRS DRS RSS %MEM COMMAND 766 ? Ssl 0:08 47 2441 545694 10448 1.0 /usr/sbin/NetworkManager --no-daemon LANG=en_US.UTF-8 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin
ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%mem 12 – print a process tree [root@rhel7 ~]# ps --forest -C sshd PID TTY TIME CMD 797 ? 00:00:00 sshd 11680 ? 00:00:03 \_ sshd 16361 ? 00:00:02 \_ sshd
[root@rhel7 ~]# ps -C sshd -L PID LWP TTY TIME CMD 797 797 ? 00:00:00 sshd 11680 11680 ? 00:00:03 sshd 16361 16361 ? 00:00:02 sshd Note – For the explanation of different column contents refer man page. How do I see all running processes in Linux?Type the ps aux to see all running process in Linux. Alternatively, you can issue the top command or htop command to view running process in Linux.
Which command would you use to view all running processes?You can use the ps command to find out which processes are running and display information about those processes. The ps command has several flags that enable you to specify which processes to list and what information to display about each process.
Which command is used to show all the current processes in Linux?To list currently running processes, use the ps , top , htop , and atop Linux commands. You can also combine the ps command with the pgrep command to identify individual processes.
How do you show all processes being run?Open the terminal window or app. To see only the processes owned by a specific user on Linux run: ps -u {USERNAME} Search for a Linux process by name run: pgrep -u {USERNAME} {processName} Another option to list processes by name is to run either top -U {userName} or htop -u {userName} commands.
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