@haokuixi
2015-03-16T14:57:53.000000Z
字数 7159
阅读 2005
linux shell
When you are using Linux command line frequently, using the history effectively can be a major productivity boost. In fact, once you have mastered the 15 examples that I've provided here, you'll find using command line more enjoyable and fun.
Typically when you type history from command line, it displays the command#(command No.) and the command. For auditing purpose, it may be beneficial to display the timepstamp along with the command as shown below.
# export HISTTIMEFORMAT='%F %T '# history | more1 2008-08-05 19:02:39 service network restart2 2008-08-05 19:02:39 exit3 2008-08-05 19:02:39 id4 2008-08-05 19:02:39 cat /etc/redhat-release
I strongly believe, this may be your most frequently used feature of history. When you've already executed a very long command, you can simply search history using a keyword and re-execute the same command without having to type it fully. 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)
Sometimes you want to edit a command from history before executing it. For e.g. you can search for httpd, which will display service httpd stop from the command history, select this command and change the stop to start and re-execute it again as shown below.
[Press Ctrl+R from the command prompt, which will display the reverse-i-search prompt]
(reverse-i-search)`httpd': service httpd stop
[Note: Press TAB(left arrow or right arrow) key when you see your command, which will display the command for you to edit, before executing it]
# service httpd start
Sometime you may end up repeating the previous commands for various reasons. Following are the 4 different ways to repeat the last executed command.
↑ to view the previous command and press enter to execute it.!! and press enter from the command line!-1 and press enter from the command line.Control+P will display the previous command, press enter to execute itIn the following example, If you want to repeat the command #4, you can do !4 as shown below.
# history | more1 service network restart2 exit3 id4 cat /etc/redhat-release# !4cat /etc/redhat-releaseFedora release 9 (Sulphur)
Type ! followed by the starting few letters of the command that you would like to re-execute. In the following example, typing !ps and enter, executed the previous command starting with ps, which is ps aux | grep yp.
# !psps aux | grep yproot 16947 0.0 0.1 36516 1264 ? Sl 13:10 0:00 ypbindroot 17503 0.0 0.0 4124 740 pts/0 S+ 19:19 0:00 grep yp
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_profileHISTSIZE=450HISTFILESIZE=450
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. I'm yet to figure out a practical use for this. I can see this getting used when you want to track commands executed from different terminals using different history file name.
# vi ~/.bash_profileHISTFILE=/root/.commandline_warrior
If you have a good reason to change the name of the history file, please share it with me, as I'm interested in finding out how you are using this feature.
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 -444 pwd45 pwd46 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 -356 export HISTCONTROL=ignoredups57 pwd [Note that there is only one pwd command in the history, even after executing pwd 3 times as shown above]58 history | tail -3
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 -338 pwd39 service httpd stop40 history | tail -3# ls -ltr# service httpd stop# history | tail -635 export HISTCONTROL=erasedups36 pwd37 history | tail -338 ls -ltr39 service httpd stop[Note that the previous service httpd stop after pwd got erased]40 history | tail -6
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. I can see lot of junior sysadmins getting excited about this, as they can hide a command from the history. It is good to understand how ignorespace works. But, as a best practice, don't hide purposefully anything from history.
# 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 -367 ls -ltr68 pwd69 history | tail -3
Sometime you may want to clear all the previous history, but want to keep the history moving forward.
# history -c
When you are searching through history, you may want to execute a different command but use the same parameter from the command that you've just searched.
In the example below, the !!:$ next to the vi command gets the argument from the previous command to the current command.
# ls anaconda-ks.cfganaconda-ks.cfg# vi !!:$vi anaconda-ks.cfg
In the example below, the !^ next to the vi command gets the first argument from the previous command (i.e cp command) to the current command (i.e vi command).
# cp anaconda-ks.cfg anaconda-ks.cfg.bakanaconda-ks.cfg# vi !^vi anaconda-ks.cfg
In the example below, !cp:2 searches for the previous command in history that starts with cp and takes the second argument of cp and substitutes it for the ls -l command as shown below.
# cp ~/longname.txt /really/a/very/long/path/long-filename.txt# ls -l !cp:2ls -l /really/a/very/long/path/long-filename.txt
In the example below, !cp:$ 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
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:
historydid not display anything
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 -379 export HISTIGNORE="pwd:ls:ls -ltr:"80 service httpd stop81 history
[Note that history did not record pwd, ls and ls -ltr]
转载自：http://www.thegeekstuff.com/2008/08/15-examples-to-master-linux-command-line-history/