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.

Table of contents

1. The easy way
2. The hackish way
3. Sources

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