Tips for viewing History records and adding timestamps in Linux

Tips for viewing History records and adding timestamps in Linux

Anyone familiar with bash must know that you can use history to output the historical commands you have entered, for example

[root@servyou_web ~]# history | more 
  6./test.sh  
  7 vim test.sh  
  8./test.sh

However, only the command is displayed here, and the time when the command was executed is not displayed, because the time is not saved in ~/.bash_history which saves the historical commands.

Add timestamp to history by setting environment variable export HISTTIMEFORMAT="%F %T `whoami` "

[root@servyou_web ~]# export HISTTIMEFORMAT="%F %T `whoami` " 
[root@servyou_web ~]# history | tail 
 1014 2011-06-22 19:17:29 root 15 2011-06-22 19:13:02 root ./test.sh  
 1015 2011-06-22 19:17:29 root 16 2011-06-22 19:13:02 root vim test.sh  
 1016 2011-06-22 19:17:29 root 17 2011-06-22 19:13:02 root ./test.sh  
 1017 2011-06-22 19:17:29 root 18 2011-06-22 19:13:02 root vim test.sh  
 1018 2011-06-22 19:17:29 root 19 2011-06-22 19:13:02 root ./test.sh  
 1019 2011-06-22 19:17:29 root 20 2011-06-22 19:13:02 root vim test.sh  
 1020 2011-06-22 19:17:29 root 21 2011-06-22 19:13:02 root ./test.sh  
 1021 2011-06-22 19:17:29 root 22 2011-06-22 19:13:02 root vim test.sh  
 1022 2011-06-22 19:25:22 root 22 2011-06-22 19:13:02 root vim test.sh  
 1023 2011-06-22 19:25:28 root history | tail

As you can see, the timestamp of the historical commands has been added, but this timestamp has not been added to .bash_history. In fact, this time record is saved in the memory of the current shell process. If you log out and log in again, you will find that the timestamps of the commands executed when you last logged in are all the same value, that is, the time when you logged out.

Nevertheless, for bash with screen, this timestamp can still be valid for a long time. After all, as long as your server is not restarted, screen will not exit, so these times can be retained for a long time. You can also use echo 'export HISTTIMEFORMAT="%F %T `whoami` "' >> /etc/profile and then source it.

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