Linux: How to include timestamps to history output

The history command in Linux and Unix-like operating systems is used to display a list of previously executed commands in the current shell session. It provides a way for users to view and access their command history, which can be useful for various purposes like recalling the syntax of a command or remember what you have run in the past, but history on its plain form does not provide timestamps so we cannot be sure when a command executed, lets see how we can change this!

Usage of the history command in bash

by just entering history in a bash shell we get a similar output, the command and its number, useful but as we said no timestamp ..

990  uptime 
  991  top 
  992  su - root 
  993  clear 
  994  su - root 
  995  exit 
  996  crontab -l 
  997  su - root 
  998  exit 
  999  su - root 
 1000  su - root 
 1001  ls 
 1002  history

How to add timestamp to history

In bash shell the environment variable that controls history command formatting is HISTTIMEFORMAT , to define timestamp along with command enter the following in the terminal

export HISTTIMEFORMAT='%F %T '

Now lets try history again, we can see that now each entry has the timestamp that the command issued

990  [08/24/23-14:23:18] uptime 
  991  [08/24/23-14:23:38] top 
  992  [08/24/23-14:24:12] su - root 
  993  [09/02/23-21:01:33] clear 
  994  [09/02/23-21:01:35] su - root 
  995  [09/02/23-21:20:01] exit 
  996  [09/05/23-15:51:59] crontab -l 
  997  [09/05/23-15:52:01] su - root 
  998  [09/06/23-11:24:10] exit 
  999  [09/18/23-14:20:38] su - root 
 1000  [09/18/23-15:43:13] su - root 
 1001  [10/02/23-15:21:57] ls 
 1002  [10/02/23-15:22:05] history

This environment variable will lost after session end so we would want to make the change permanent, to do this append the environment variable to ~/.bashrc , this file is readed every time a user starts a new bash session.

History command in other shells

Other shells like zsh and fish have a history command as well but they use a different environment variable to modify its formatting

Zsh Shell

If you’re using the Zsh shell, you can achieve the same by adding the following line to your ~/.zshrc file:

HIST_STAMPS="yyyy-mm-dd HH:MM:SS"

Fish Shell

Fish shell stores its history differently, and you can enable timestamps using the following commands:

set -U fish_history show_time yes  
set -U fish_history time_format '%Y-%m-%d %T '

Now, you should be able to use the history command in your shell to view your command history with timestamps included. Each command will be preceded by a timestamp indicating when it was executed.

Conclusion

In this article we saw how we can modify the history environment variable options to add timestamp formatting, quite easy to add a very useful feature! i hope you enjoyed this article as much i enjoyed writing the article!