Brief Introduction to Linux Process Operation commands

Linux Process Management is a very important task and can help us better control the system. A process is an execution activity of a program on a computer. When you run a program, you start a process. Common process operation commands are described here.

Linux Process Operation Command 1: Ps Process status query command.

Command Format # ps [[Option]

Common options:
●-A: displays all user processes.
●-E: displays the process environment variables.
●-L, which provides a long list.
●-R: only running processes are displayed.
●-S, increase the CPU time and page error.
●-W: display the output in width format. By default, if the output result cannot be displayed in one row, the result output is shortened. This option can be used to avoid this problem.
●-Txx: Only processes controlled by tty. xx are displayed.
●-U: print the user format and display the user name and process start time.
●-X: displays processes without control terminals.

Command instructions:

Example:

Example A: all processes are displayed on the page, and the user name and start time of the process are displayed. The command is as follows:

 
 

  
  
#ps -axu | more  
  
  
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND  
  
  
root 1 0.2 0.1 1388 492 ? S 22:06 0:04 init  
  
  
root 2 0.0 0.0 0 0 ? SW 22:06 0:00 [keventd]  
  
  
root 3 0.0 0.0 0 0 ? SWN 22:06 0:00 [ksoftirqd/0]  
  
  
root 4 0.0 0.0 0 0 ? SW 22:06 0:00 [kswapd]  
  
  
root 5 0.0 0.0 0 0 ? SW 22:06 0:00 [bdflush]  
  
  
root 6 0.0 0.0 0 0 ? SW 22:06 0:00 [kupdated]  
  
  
root 8 0.0 0.0 0 0 ? SW 22:06 0:00 [kjournald]  
  
  
root 1077 0.0 0.1 1360 400 tty4 S 22:09 0:00  
  
  
/sbin/mingetty tty4  
  
  
root 1078 0.0 0.1 1360 400 tty5 S 22:09 0:00  
  
  
/sbin/mingetty tty5  
  
  
root 1079 0.0 0.1 1360 400 tty6 S 22:09 0:00  
  
  
/sbin/mingetty tty6  
  
  
........  
 
 

Description of the ps command output field:
● USER: the USER name of the process owner.
● PID and process ID, which can uniquely identify the process.
● % CPU, percentage of CPU time and total time occupied by the process since the last refresh.
● % MEM, percentage of memory used by processes.
● VSZ: the virtual memory used by the process, in the unit of K.
● RSS: the total number of physical memory occupied by processes, in K.
● TTY: the terminal name related to the process.
● STAT, Process status, used (R -- run or prepare to run; S -- sleep status; I -- idle; Z -- frozen; D -- uninterrupted sleep; w-the process does not reside on the page; T stops or tracks .) These letters.
● START: the process START time.
● TIME: the total cpu time used by the process.
● COMMAND: the COMMAND line to be executed.

Linux Process Operation Command 2: Kill the process command.

Command Format: # kill [[Option] [[Signal] <process number>

Common options:
●-S: Specifies the signal to be sent. It can be either a signal name or a number.
●-P: specify that the kill command only displays the PID of the process and does not actually send the end signal.
●-L: print the signal table that can be sent by kill, which can be found in the/usr/include/linux/signal. h file.

[[Signal]

Sends an optional signal. The default value is SIGTERM. The other two commonly used values are SIGHUP (the device that the modem suspends by phone) and SIGKILL (which cannot be ignored by the process ).

Command instructions:

Use this command to end the running program, which can achieve the "Task Manager" function in windows. Especially when a process is always running with no results like a dead machine, this command may kill the process and restore the system to normal.

Example:

Example A: Kill the cupsd process in Example. The command is as follows:

# Killed 945

Example B: display all kill signals.

 
 

  
  
#kill -l  
  
  
1) SIGHUP 2) SIGINT 3) SIGQUIT 4) SIGILL  
  
  
5) SIGTRAP 6) SIGABRT 7) SIGBUS 8) SIGFPE  
  
  
9) SIGKILL 10) SIGUSR1 11) SIGSEGV 12) SIGUSR2  
  
  
13) SIGPIPE 14) SIGALRM 15) SIGTERM 17) SIGCHLD  
  
  
18) SIGCONT 19) SIGSTOP 20) SIGTSTP 21) SIGTTIN  
  
  
22) SIGTTOU 23) SIGURG 24) SIGXCPU 25) SIGXFSZ  
  
  
26) SIGVTALRM 27) SIGPROF 28) SIGWINCH 29) SIGIO  
  
  
30) SIGPWR 31) SIGSYS 35) SIGRTMIN 36) SIGRTMIN+1  
  
  
37) SIGRTMIN+2 38) SIGRTMIN+3 39) SIGRTMIN+4 40) SIGRTMIN+5  
  
  
41) SIGRTMIN+6 42) SIGRTMIN+7 43) SIGRTMIN+8 44) SIGRTMIN+9  
  
  
45) SIGRTMIN+10 46) SIGRTMIN+11 47) SIGRTMIN+12 48) SIGRTMIN+13  
  
  
49) SIGRTMIN+14 50) SIGRTMAX-14 51) SIGRTMAX-13 52) SIGRTMAX-12  
  
  
53) SIGRTMAX-11 54) SIGRTMAX-10 55) SIGRTMAX-9 56) SIGRTMAX-8  
  
  
57) SIGRTMAX-7 58) SIGRTMAX-6 59) SIGRTMAX-5 60) SIGRTMAX-4  
  
  
61) SIGRTMAX-3 62) SIGRTMAX-2 63) SIGRTMAX-1  
 
 

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