Linux/Unix - How To View And Clear Command History

In Linux/Unix based system, command history of a session can be viewed using "history" command. Command history will be displayed with line number, highest line number is the last executed command.

Complete command history can be cleared using "history -c" command. Specific command line history can be deleted using command "history -d <line-number/offset>".

Syntax:

history

 

Usage:

history [-c] [-d offset] [n] or history -awrn [filename] or history -ps arg [arg...]

 

Example:

[user@Linux]# history
    1  pwd
    2  ls -lh
    3  cd /var/log
    4  top
    5  history
[user@Linux]#

!! Delete line number 2 using command "history -d 2" !!

[user@Linux]# history -d 2

[user@Linux]# history
    1  pwd
    2  cd /var/log
    3  top
    4  history

    5  history -d 2

    6  history
[user@Linux]#

!! Clear complete command history using command "history -c" !!

[user@Linux]# history -c

[user@Linux]# history
    1  history
[user@Linux]#

!! Display timestamp using HISTTIMEFORMAT !! 
 

[user@Linux]# export HISTTIMEFORMAT='%F %T '
[user@Linux]# history | more
    1  2015-03-05 15:02:39 who
    2  2015-03-05 15:02:42 ls -l
    3  2015-03-05 15:02:50 pwd
    4  2015-03-05 15:02:52 export HISTTIMEFORMAT='%F %T '
    5  2015-03-05 15:02:53 history | more

[user@Linux]#

[user@Linux]# export HISTTIMEFORMAT=' '
[user@Linux]# history
    1  who
    2  ls -l
    3  pwd
    4  export HISTTIMEFORMAT='%F %T '
    5  history | more

    6  export HISTTIMEFORMAT=' '

    7  history

[user@Linux]#