15 Examples To Master Linux Command Line History

Hi all,

This article will teach you to beacome a master in Lnux command line history.


15 Examples To Master Linux Command Line History
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1. Display timestamp using HISTTIMEFORMAT
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# export HISTTIMEFORMAT='%F %T '
# history | more
1 2008-08-05 19:02:39 service network restart
2 2008-08-05 19:02:39 exit
3 2008-08-05 19:02:39 id
4 2008-08-05 19:02:39 cat /etc/redhat-release

2. Search the history using Control+R
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Press Control+R and type the keyword. In the following example, I searched for red, which displayed the previous command “cat /etc/redhat-release” in the history that contained the word red.

# [Press Ctrl+R from the command prompt,
which will display the reverse-i-search prompt]
(reverse-i-search)`red': cat /etc/redhat-release
[Note: Press enter when you see your command,
which will execute the command from the history]
# cat /etc/redhat-release
Fedora release 9 (Sulphur)

3. Repeat previous command quickly using 4 different methods
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1. Use the up arrow to view the previous command and press enter to execute it.
2. Type !! and press enter from the command line
3. Type !-1 and press enter from the command line.
4. Press Control+P will display the previous command, press enter to execute it

4. Execute a specific command from history
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In the following example, If you want to repeat the command #4, you can do !4 as shown below.

# history | more
1 service network restart
2 exit
3 id
4 cat /etc/redhat-release

# !4
cat /etc/redhat-release
Fedora release 9 (Sulphur)

5. Execute previous command that starts with a specific word
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# !ps
ps aux | grep yp
root 16947 0.0 0.1 36516 1264 ? Sl 13:10 0:00 ypbind
root 17503 0.0 0.0 4124 740 pts/0 S+ 19:19 0:00 grep yp

6. Control the total number of lines in the history using HISTSIZE
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Append the following two lines to the .bash_profile and relogin to the bash shell again to see the change. In this example, only 450 command will be stored in the bash history.

# vi ~/.bash_profile
HISTSIZE=450
HISTFILESIZE=450

7. Change the history file name using HISTFILE

By default, history is stored in ~/.bash_history file. Add the following line to the .bash_profile and relogin to the bash shell, to store the history command in .commandline_warrior file instead of .bash_history file

# vi ~/.bash_profile
HISTFILE=/root/.commandline_warrior

8. Eliminate the continuous repeated entry from history using HISTCONTROL
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In the following example pwd was typed three times, when you do history, you can see all the 3 continuous occurrences of it. To eliminate duplicates, set HISTCONTROL to ignoredups as shown below.

# pwd
# pwd
# pwd
# history | tail -4
44 pwd
45 pwd
46 pwd [Note that there are three pwd commands in history, after
executing pwd 3 times as shown above]
47 history | tail -4

# export HISTCONTROL=ignoredups
# pwd
# pwd
# pwd
# history | tail -3
56 export HISTCONTROL=ignoredups
57 pwd [Note that there is only one pwd command in the history, even after
executing pwd 3 times as shown above]
58 history | tail -4

9. Erase duplicates across the whole history using HISTCONTROL
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The ignoredups shown above removes duplicates only if they are consecutive commands. To eliminate duplicates across the whole history, set the HISTCONTROL to erasedups as shown below.

# export HISTCONTROL=erasedups
# pwd
# service httpd stop
# history | tail -3
38 pwd
39 service httpd stop
40 history | tail -3

# ls -ltr
# service httpd stop
# history | tail -6
35 export HISTCONTROL=erasedups
36 pwd
37 history | tail -3
38 ls -ltr
39 service httpd stop
[Note that the previous service httpd stop after pwd got erased]
40 history | tail -6

10. Force history not to remember a particular command using HISTCONTROL
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When you execute a command, you can instruct history to ignore the command by setting HISTCONTROL to ignorespace AND typing a space in front of the command as shown below

# export HISTCONTROL=ignorespace
# ls -ltr
# pwd
# service httpd stop [Note that there is a space at the beginning of service,
to ignore this command from history]
# history | tail -3
67 ls -ltr
68 pwd
69 history | tail -3

11. Clear all the previous history using option -c
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Sometime you may want to clear all the previous history, but want to keep the history moving forward.

# history -c

12. Subtitute words from history commands
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In the example below, the !!:$ next to the vi command gets the argument from the previous command to the current command.

# ls anaconda-ks.cfg
anaconda-ks.cfg
# vi !!:$
vi anaconda-ks.cfg

In the example below, the !^ next to the vi command gets the first argument from the previous command (i.e cp command) to the current command (i.e vi command).

# cp anaconda-ks.cfg anaconda-ks.cfg.bak
anaconda-ks.cfg
# vi !^
vi anaconda-ks.cfg

13. Substitute a specific argument for a specific command.
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In the example below, !cp:2 searches for the previous command in history that starts with cp and takes the second argument of cp and substitutes it for the ls -l command as shown below.

# cp ~/longname.txt /really/a/very/long/path/long-filename.txt
# ls -l !cp:2
ls -l /really/a/very/long/path/long-filename.txt
In the example below, !cp:$ searches for the previous command in history that starts with cp and takes the last argument (in this case, which is also the second argument as shown above) of cp and substitutes it for the ls -l command as shown below.

# ls -l !cp:$
ls -l /really/a/very/long/path/long-filename.txt

14. Disable the usage of history using HISTSIZE
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If you want to disable history all together and don’t want bash shell to remember the commands you’ve typed, set the HISTSIZE to 0 as shown below.

# export HISTSIZE=0
# history
# [Note that history did not display anything]

15. Ignore specific commands from the history using HISTIGNORE
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Sometimes you may not want to clutter your history with basic commands such as pwd and ls. Use HISTIGNORE to specify all the commands that you want to ignore from the history. Please note that adding ls to the HISTIGNORE ignores only ls and not ls -l. So, you have to provide the exact command that you would like to ignore from the history.

# export HISTIGNORE="pwd:ls:ls -ltr:"
# pwd
# ls
# ls -ltr
# service httpd stop

# history | tail -3
79 export HISTIGNORE="pwd:ls:ls -ltr:"
80 service httpd stop
81 history
[Note that history did not record pwd, ls and ls -ltr]