History will shows the list of commands which you have executed previously. Would you like to view information on when you executed these commands,

A few different uses of history command as below,

Here, have different types of time format for displaying History command,

%d - Day
%m - Month
%y - Year
%T - Time
%H - Hours
%M - Minutes
%S - Seconds
%F for setting year/month/day

Basic History command:



history

   18  exim -bpc

   19  exim -bp

   20  exim -bp | awk '/^ *[0-9]+[mhd]/{print "exim -Mrm " $3}' | bash

   21  service exim restart

   22  pgrep -f httpd

   23  pgrep -f proftpd


Few types of time format for history command,
 
export HISTTIMEFORMAT="%F %T "


history  

 1002  2014-06-24 18:27:49 ls -al

 1003  2014-06-24 18:27:51 free -m

 1004  2014-06-24 18:27:52 df -h

 1005  2014-06-24 18:27:56 fdisk -l

 1006  2014-06-24 18:28:03 ls

 1007  2014-06-24 18:28:10 du -sch *
export  HISTTIMEFORMAT="%h/%d - %H:%M:%S"


history

 1002  Jun/24 - 18:32:25  free -m

 1003  Jun/24 - 18:32:27  top -c

 1004  Jun/24 - 18:32:33  fdisk -l

 1005  Jun/24 - 18:32:44  netstat -anp | grep httpd

 1006  Jun/24 - 18:32:50  ps aux | grep php

 1007  Jun/24 - 18:33:04  du -sch *
export HISTTIMEFORMAT='%r-%d-%b-%Y '


history

  1017  06:49:09 PM IST-24-Jun-2014 history 20

 1018  06:51:56 PM IST-24-Jun-2014 ls

 1019  06:52:59 PM IST-24-Jun-2014 df -h

 1020  06:54:48 PM IST-24-Jun-2014 ps aux | grep java

 1021  06:57:27 PM IST-24-Jun-2014 history | tail -5

 1022  06:58:48 PM IST-24-Jun-2014 du -sch *
export HISTTIMEFORMAT="%T "


history

  1017  18:49:09 history 20

 1018  18:51:56 ls

 1019  18:52:59 df -h

 1020  18:54:48 ps aux | grep java

 1021  18:57:27 history | tail -5

 1022  18:58:48 du -sch *

 1023  19:01:56 man strftime

Open the /etc/bashrc file in a text editor and add the above export HISTTIMEFORMAT , Once you have updated to that file  check on new console.

Search command from history using grep command :


history | grep httpd

  266  2014-06-24 17:28:46  /etc/init.d/httpd restart

  753  2014-06-24 17:28:46  /etc/init.d/httpd stop

  812  2014-06-24 17:28:46  vim /etc/httpd/conf/httpd.conf

Get command using head and tail :

You probably do not need to see all of the last 1000 commands, would you like to see first and  previous 20 commands you typed are displayed  
 history 10 or


history | tail -50

 1003  2014-06-24 18:39:49  df -h

 1004  2014-06-24 18:40:15  export HISTIGNORE='ls -l:pwd:date:'

 1005  2014-06-24 18:40:17  history

 1006  2014-06-24 18:42:13  history | grep httpd

 1007  2014-06-24 18:44:18  du -sch *





history | head -5

   11  2014-06-24 17:28:46  ls

   12  2014-06-24 17:28:46  cd -

   13  2014-06-24 17:28:46  ls

   14  2014-06-24 17:28:46  rm -rf hioxindia/

   15  2014-06-24 17:28:46  ls

Restore default format:
 
export HISTTIMEFORMAT=""



history

 1017  history 20

 1018  ls

 1019  df -h

 1020  ps aux | grep java

 1021  history | tail -5

 1022  du -sch *

Execute command from the history list :

!! is executes the last command in the history.
 
# !!
du -sch *

Executes the command from the history file which is given number with !
 
# !1003  
df -h  

executes a command which is  most recent matching string from the history.
 
# !ps
ps aux | grep java

If you press CTRL-R key to perform a “reverse-i-search”.

Then press right Arrow key just displaying command not execute or if press enter command it will be executed.

Manage total number of History size stored :

Add the following line to the .bash_profile and relogin to the bash shell, this configuration only 700 command only stores.
 
HISTSIZE=700
HISTFILESIZE=700

HISTSIZE - Manage how many history commands to stores current session in the history file.

HISTFILESIZE - Manage  how many history commands to keep in HISTFILE

List out history command for root :
 
# cat  ~/.bash_history

Delete or Clear History of Commands:
 
#  history -c