History command in unix

Jump to navigation. As I spend more and more time in terminal sessions, it feels like I'm continually finding new commands that make my daily tasks more efficient. The GNU history command is one that really changed my work day. The GNU history command keeps a list of all the other commands that have been run from that terminal session, then allows you to replay or reuse those commands instead of retyping them.

history command in unix

If you are an old greybeard, you know about the power of historybut for us dabblers or new sysadmin folks, history is an immediate productivity gain. To see history in action, open a terminal program on your Linux installation and type:. The joy of history is that now you can replay any of them by using a command such as:.

I could also access that command by entering:. You can also use history to rerun the last command you entered by typing!! For example:. Another way to get to this search functionality is by typing Ctrl-R to invoke a recursive search of your command history. After typing this, the prompt changes to:. Now you can start typing a command, and matching commands will be displayed for you to execute by pressing Return or Enter.

There may come a time that you want to remove some or all the commands in your history file. To clear the entire contents of the history file, execute history -c. The history file is stored in a file that you can modify, as well. Bash shell users will find it in their Home directory as. For more information about the history command and other interesting things you can do with it, take a look at the GNU Bash Manual.

I alias "wdil" to "history grep" to search for past commands, but the Ctrl-R method is even slicker. How to use the history command in Linux How to use the history command in Linux. Become more efficient at the command prompt with the powerful history command. Image by :. Internet Archive Book Images.

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Command line. About the author.We use history command frequently in our daily routine jobs to check history of command or to get info about command executed by user. In this post, we will see how we can use history command effectively to extract the command which was executed by users in Bash shell.

This may be useful for audit purpose or to find out what command is executed at what date and time. Executing simple history command from terminal will show you a complete list of last executed commands with line numbers. How to find date and timestamp against command? As we can see same command is being repeated number of times in above output. How to filter simple or non destructive commands in history?. With the below command will help us to ignore duplicate commands entry made by user.

Only single entry will be shown in history, if a user execute a same command multiple times in a Bash Prompt. Unset export command on the fly. Execute unset export command with variable one by one whatever commands have been exported by export command.

history command in unix

How to see command history executed by a specific user. We can view or open file to see the command history. Some organization do not keep history of commands because of security policy of the organization. In this case, we can edit. The change in file will effect globally. With up and down arrow, we can see previously used command which may be helpful or may irate you. Recall a previously used specific command.

Using 'history' to Repeat Commands

Combination of Bang and 8! We have tried to highlight power of history command. However, this is not end of it.

Please share your experience of history command with us through our comment box below. TecMint is the fastest growing and most trusted community site for any kind of Linux Articles, Guides and Books on the web. Millions of people visit TecMint! If you like what you are reading, please consider buying us a coffee or 2 as a token of appreciation. We are thankful for your never ending support. View all Posts.

Narad always believes sharing IT knowledge with others and adopts new technology with ease. Your name can also be listed here. Got a tip? Submit it here to become an TecMint author. How can I filter a many of commands in history?

history command in unix

Great stuff! It is also proper grammar. Log-in to that user 2.Ever want to repeat the command you just entered? The "history" command gives you a method for repeating commands entered earlier in your session. The C shell will keep a record of your most recent commands and allow you to reuse them. You can control how many commands are remembered by putting a command in your. This statement tells the C Shell that you would like to keep track of the last 23 commands you have given the system.

Twenty-three is a good number to use here as most CRT terminals can hold only 24 lines of text; therefore, setting "history" to 23 gives you a full screen of previous commands plus the prompt. To see this history listing, enter the command "history". You should see a display like this one.

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This user has performed twelve jobs there have been twelve "events" since he signed on. Notice that the system lists "history" as the most recent command. However, the following information should be sufficient for most users. There are three parts to the statement which you use to access the history list:. Note that you separate these three variables from each other by colons. The historical reference begins with an exclamation mark at the beginning of the command.

The characters typed immediately after the exclamation mark identify the event you wish to refer to. Here are the four most common ways you can tell the system to reference your history list:. Note that the first three examples above are all ways to repeat command 11 from the sample history list.

You would choose one of these commands since all three commands are shorthand for "vi uhist. Note that the fourth example, "! Frequently, however, you do not want to repeat a command verbatim but need to modify it in some way: for instance, you might want to replace one argument, add another, or correct a spelling mistake.

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Adding something to the end of a repeated command is easy: just reference the command and append what you wish to add. Modifying commands or correcting errors is a little more involved; you must use the other two variables as well as the historical reference.

You must tell the system what word or words you wish to reuse from the command you have referred to. Here is a list of the more useful word references:. Next, you must tell the system what modifications to make. There are many "modifiers" you could use, but the most useful is "s", short for "substitute":.

Using 'history' to Repeat Commands Ever want to repeat the command you just entered? A complete description of "history" can be found in the man page for the C shell. Enter man csh This help text provides a brief overview of "history".In this article, we will show you two simple ways to clear your command-line history on a Linux system. The major reason for removing command-line history from the Linux terminal is to prevent another user, who could be using the same account.

Take a look at the command below, here the user aaronkilik has typed the database server password on the command line. If you look into th bash history file towards the end, you will see the password typed above in there. To remove a single line from the history file, use the -d option.

For example, if you want to clear a command where you entered clear-text password as in the scenario above, find the line number in the history file and run this command. To delete or clear all the entries from bash history, use the history command below with the -c option.

Alternatively, you can use the command below to delete history of all last executed commands permanently in the file. Always remember that all commands you run are recorded in a history file, so do not type plain-text passwords on the command line. If you have questions or thoughts to share with us, make use of the feedback form below. TecMint is the fastest growing and most trusted community site for any kind of Linux Articles, Guides and Books on the web.

Millions of people visit TecMint! If you like what you are reading, please consider buying us a coffee or 2 as a token of appreciation. We are thankful for your never ending support.

Tags: Linux Tricks. View all Posts. Aaron Kili is a Linux and F. S enthusiast, an upcoming Linux SysAdmin, web developer, and currently a content creator for TecMint who loves working with computers and strongly believes in sharing knowledge. Your name can also be listed here. Got a tip? Submit it here to become an TecMint author. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment.

Notify me of followup comments via e-mail. You can also subscribe without commenting.Joinsubscribers and get a daily digest of news, geek trivia, and our feature articles. Once you understand the Linux history command and how to use it, it can significantly boost your productivity.

It allows you to review and repeat your previous commands. The lengthier and more complicated a command is, the harder it is to remember and type without making an error. There are two types of errors: one that prevents the command from working, and one that allows the command to work, but makes it do something unexpected.

However, if you learn how to use the history command, it can improve your use of the Linux command line, every single day.

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The commands are numbered, with the most recently used those with the highest numbers at the end of the list. To see a certain number of commands, you can pass a number to history on the command line.

You can achieve the same result if you pipe history through the tail command. To do so, type the following:. If you want to reuse a command from the history list, type an exclamation point!

history command in unix

This can be useful when you issue a command and forget to use sudo. Type sudoone space, the double exclamation points, and then hit Enter. For the following example, we typed a command that requires sudo. So, you can type the corresponding number from the list to repeat a command or use the double exclamation points to repeat the last command you used. However, what if you want to repeat the fifth or eighth command? You can use one exclamation point, a hyphen -and the number of any previous command again, without spaces to repeat it.

To repeat the last command that starts with a particular string, you can type an exclamation point, and then the string with no spaces, and then hit Enter. For example, to repeat the last command that started with sudoyou would type this command:.

To provide a safety net, though, you can use the :p print modifier, as shown below:. This instructs history to print the command to the terminal window, rather than executing it. This allows you to see the command before you use it. If it is the command you want, press the Up arrow, and then hit Enter to use it. If you want to find a command that contains a particular string, you can use an exclamation point and question mark.

An interactive search allows you to hop through a list of matching commands and repeat the one you want. As you type the search clue, the first matching command will appear. The matching commands update as you type each letter. You can use other Linux tools to search the history list. This a great trick to have up your sleeve for whenever you misspell a command or want to rerun one with a different command-line option or parameter.In computingvarious shells maintain a record of the commands issued by the user during the current session.

The history command works with the command history list. When the command is issued with no options, it prints the history list. Users can supply options and arguments to the command to manipulate the display of the history list and its entries. The operation of the history command can also be influenced by a shell's environment variables. For example, an environment variable can be set to control the number of commands to retain in the list.

In early versions of Unix the history command was a separate program. However, most shells have long included the history command as a shell built-inso the separate program is no longer in common use.

Since most current history commands are shell built-ins, details depend on the choice of shell. The history command has the following syntax in bash : [5]. The history command has the following syntax in tcsh :. The first form prints the history event list.

If n is given only the n most recent events are printed or saved. With -hthe history list is printed without leading numbers. If -T is specified, timestamps are printed also in comment form. This can be used to produce files suitable for loading with 'history -L' or 'source -h'. With -r, the order of printing is most recent first rather than oldest first.

With -Sthe second form saves the history list to filename. If the first word of the savehist shell variable is set to a number, at most that many lines are saved.

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Currently it succeeds only when the shells quit nicely one after another. With -Lthe shell appends filename, which is presumably a history list saved by the -S option or the savehist mechanism, to the history list. If histlit is set, the first and second forms print and save the literal unexpanded form of the history list.

In PowerShellhistory is a predefined command alias for the Get-History cmdlet. From Wikipedia, the free encyclopedia. Redirected from History Unix. University of Washington. Retrieved 25 July Archived PDF from the original on Retrieved Unix command-line interface programs and shell builtins.

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It only takes a minute to sign up. I want to see what are the last N commands in my history. I thought history tail -n 5 would make it, but I noticed that a multiline command counts for as many lines as it has. When you apply history it will show last history command as well. To prevent that space waster such alias could be handy:.

Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. How to get last N commands from history? Ask Question. Asked 4 years, 9 months ago. Active 1 year, 1 month ago. Viewed 67k times. Gilles 'SO- stop being evil' k gold badges silver badges bronze badges.

The Power of Linux “History Command” in Bash Shell

Active Oldest Votes. I found it! That seems to be for tcshyash and bash. You may want to give the corresponding information for other shells like zshfishkshand the POSIX way.

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I would love to, although I don't have any of these installed in my computer.


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