Linux Process Management

Linux Process Management

Linux Process Management is a function of the Linux kernel.

1. ps command: process state

SysV style:-is required for each option-
BSD style:-is not required for each option-

A: Show All terminal-related processes u: x: All terminal-independent processes-e: show all processes-F: Extra full format-l:

2. Process classification:

Terminal-related processes
Processes unrelated to the terminal

3. Process status:

D: uninterrupted sleep
R: running or ready
S: resumable sleep
T: Stop
Z: Zombie

<: High-priority process N: low-priority process +: foreground process group process l: multithreading process s: Session Process

4. pstree: displays the process tree.

5. pgrep: display processes in grep Style

6. pidof: displays the PID of the running program.

Pidof init
Pidof sshd

7. top:

M: sort by resident memory size
P: sort by CPU usage percentage
T: sort by accumulative time

L: whether to display the average load and start time t: whether to display information related to CPU status m: whether to Display memory information c: whether to display the complete command line information q: topk: terminate a process-d: Change the refresh delay duration-B: Display in batch mode-n #: display only in batch mode # batch

8. important signals:

1: SIGHUP: enables a process to repeat the configuration file without restarting and make the new configuration take effect;
2: SIGINT: Ctrl + c, terminate
9: SIGKILL: killing a process
15: SIGTERM: terminate a process (default signal)

Specify a signal:
Signal Number: kill-1
Signal name: kill-SIGKILL
Abbreviated signal name: kill-KILL

9. killall COMMAND: Kill all processes named COMMAND.

10. Adjust the nice value:

Adjust the nice value of the started process:
Renice NI PID
Specify nice value at startup:
Nice-n NI COMMAND

11. vmstat: Command for viewing system status

12. foreground-> background:

Ctrl + z
COMMAND &
Bg: Stop the job in the background to continue running.

Jobs: view all jobs in the background
Job is good, different from process number
+: Commands are used to operate jobs by default.
-: The command is used to set the job for the second default operation.
Fg: re-transfer the background job back to the foreground
Fg [[%] jobid], % in the middle can be omitted, but if it is used on the kill command, the % number cannot be omitted, it is assumed that the corresponding process is terminated by default, such:
Kill 2 indicates killing the process whose PID is 2, rather than killing the job whose job number is 2.