oam/knowledge base/find how long a process has run.md

Find how long a process has run in UNIX

UNIX and Linux have commands for almost everything; if there is no command, you can check some important files in the /etc directory or in the /proc virtual filesystem to find out some useful information.

The easy way

If the program started today, ps also shows when:

$ ps -ef
UID        PID  PPID  C STIME TTY          TIME CMD
user     11610 11578  0 Aug24 ?        00:08:06 java -Djava.library.path=/usr/lib/jni:/usr/lib/alpha-linux-gnu/jni...
user     17057 25803  0 13:01 ?        00:00:24 /usr/lib/chromium-browser/chromium-browser

The hackish way

Useful if the process started before today:

1. find the process ID

   $ ps -ef | grep java
   user 22031 22029   0   Jan 29 ? 24:53 java -Xms512M -Xmx512 Server
   
   $ pgrep -l java
   22031 java
   

2. look into the proc virtual filesystem for that process and check the creation date, which is when the process was started

   ls -ld /proc/22031
   dr-x--x--x   5 user     group           832 Jan 22 13:09 /proc/22031
   

Sources

• how to find how long a process has run in unix