Linux command ps

ps(process status)

說明：用來顯示執行緒的資訊

支援多種options：
UNIX options
BSD options
GNU long options

使用概念

• 選擇process，simple selection / selection by list
• 輸出格式控制(format)

Simple selection 詳細參考man ps

 a      Lift the BSD-style "only yourself" restriction, 
             which is imposed upon the set of all processes when some BSD-style (without "-") 
             options are used or when the ps personality setting is BSD-like.  
             The set of processes selected in this manner is in addition to the set of processes selected by other means.  
             An alternate description is that this option causes ps to list all processes with a terminal (tty), 
             or to list all processes when used together with the x option.

       -A     Select all processes.  Identical to -e.

       -a     Select all processes except both session leaders (see getsid(2)) and processes not associated with a terminal.

       -d     Select all processes except session leaders.

       --deselect
              Select all processes except those that fulfill the specified conditions (negates the selection).  
              Identical to -N.

       -e     Select all processes.  Identical to -A.

       g      Really all, even session leaders.  This flag is obsolete and may be discontinued in a future release.  
              It is normally implied by the a flag, and is only
              useful when operating in the sunos4 personality.

       -N     Select all processes except those that fulfill the specified conditions (negates the selection).  
              Identical to --deselect.

       T      Select all processes associated with this terminal.  Identical to the t option without any argument.

       r      Restrict the selection to only running processes.

       x      Lift the BSD-style "must have a tty" restriction, which is imposed upon the set of all processes 
              when some BSD-style (without "-") options are used or
              when the ps personality setting is BSD-like.  The set of processes selected in this manner is in addition 
              to the set of processes selected by other means.
              An alternate description is that this option causes ps to list all processes owned by you (same EUID as ps), 
              or to list all processes when used together
              with the a option.

Selection by list

 ps -p "1 2" -p 3,4
       -123   Identical to --pid 123.
       123    Identical to --pid 123.
-C cmdlist
              Select by command name.  This selects the processes whose executable name is given in cmdlist.
-g grplist
              Select by session OR by effective group name.  Selection by session is specified by many standards, 
              but selection by effective group is the logical behavior that several other operating systems use.  
              This ps will select by session when the list is completely numeric (as sessions are).  Group ID
              numbers will work only when some group names are also specified.  See the -s and --group options.
p pidlist
              Select by process ID.  Identical to -p and --pid.

--sid sesslist
              Select by session ID.  Identical to -s.

-u userlist
              Select by effective user ID (EUID) or name.  This selects the processes 
              whose effective user name or ID is in userlist.

Output control

-f Do full-format listing. 
        This option can be combined with many other UNIX-style options to add additional columns.  
        It also causes the command arguments to be printed.  
        When used with -L, the NLWP (number of threads) and LWP (thread ID) columns will be added.  
        See the c option, the format keyword args, and the format keyword comm.
-F Extra full format.
-j Jobs format
 -o format List user-defined format. 

EXAMPLES

顯示使用者當次登入資訊

[root@li1548-65 live]# ps
  PID TTY          TIME CMD
24539 pts/1    00:00:00 bash
24761 pts/1    00:00:00 ps

列出最耗費記憶體的執行緒

ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%mem | head

-e：輸出所有行程
-o：指定輸出欄位，後面接著所有想要輸出的欄位名稱：
pid：行程 ID（process ID）
ppid：父行程 ID（parent process ID）
cmd：程式名稱
%mem：記憶體使用量（百分比）
%cpu：CPU 使用量（百分比）

--sort 參數則是指定排序的依據欄位，
預設會依照數值由小到大排序，
若要由大到小則在欄位名稱前加負號。
-%mem，就是記憶體使用量從大到小排序。

  PID  PPID CMD                         %MEM %CPU
 2124  1278 /usr/lib/chromium-browser/c 25.0 14.4
 1446  1278 /usr/lib/chromium-browser/c 21.5 15.4
 1253     1 /usr/lib/chromium-browser/c 19.2 13.0
 1328  1278 /usr/lib/chromium-browser/c  7.6  2.9
 1392  1278 /usr/lib/chromium-browser/c  7.6  0.5
  732   669 /usr/bin/X :0 -seat seat0 -  5.7  2.0
 1060     1 /usr/lib/arm-linux-gnueabih  1.8  0.0
 1086   758 pcmanfm --desktop --profile  1.5  0.2
 1085   758 lxpanel --profile LXDE-pi    1.5  0.3

輸出pid,ppid,cpu,mem,起始時間....

ps -eo uname,pid,ppid,nlwp,pcpu,pmem,psr,start_time,tty,time,args

USER   PID  PPID NLWP %CPU %MEM PSR START TT       TIME COMMAND
root     1     0    1  0.0  0.1   1 Feb20 ?    00:00:01 /sbin/init
root     2     0    1  0.0  0.0   0 Feb20 ?    00:00:00 [kthreadd]
root     3     2    1  0.0  0.0   0 Feb20 ?    00:02:23 [ksoftirqd/0]
root     6     2    1  0.0  0.0   0 Feb20 ?    00:00:00 [migration/0]
root     7     2    1  0.0  0.0   1 Feb20 ?    00:00:00 [migration/1]
root     9     2    1  0.1  0.0   1 Feb20 ?    00:13:52 [ksoftirqd/1]

列出記憶體使用

ps aux | grep apache2 | awk '{ total += $6; } END { print total/1024"MB" }'


//寫成function
$ vim .bashrc

function memusage() {
    ps aux | grep "$1" | awk '{ total += $6; } END { print total/1024"MB" }'
}

//用法
memusage apache2  //就可以印出記憶體使用量

列出CPU使用

ps aux | grep apache2 | awk '{ total += $3; } END { print total"%" }'

//寫成function
$ vim .bashrc
function cpuusage() {
    ps aux | grep "$1" | awk '{ total += $3; } END { print total"%" }'
}

cpuusage apache2 # 就可以印出總 CPU 使用量
註：cpu 算法是比較奇怪(因為包含多顆 CPU)，不過可以把自己的 CPU 數量 * 100%，再來看這個比例。