Bash History: How to Effectively Clear Your History

Bash History: How to Effectively Clear Your History

Bash history, also known as the command history, is the record of all of the commands you’ve typed in the terminal at your computer. When you type history into the command line, it returns all of the commands you’ve entered that are currently stored in your bash history, which allows you to scroll up through them and execute them again if necessary. Sometimes you may find that you accidentally enter an embarrassing or otherwise inappropriate command into your bash history, and wish to clear it out so that nobody else can see it by using the history -c command in Linux.

Understand Where Bash Stores Information

In order to clear your bash history, you need to understand where bash stores information. By default, when you open a new terminal session, bash looks for a file called .bash_history in your home directory. If this file exists, it will be used to store a list of the commands you have typed during that session. Once the session is closed, the .bash_history file is updated with the new commands.

The command line interface (CLI) also has the ability to create temporary files containing the executed commands. These are stored in a directory with the same name as your user account, but typically hidden from view by default on Mac OS X and Linux systems.

It’s also worth noting that bash stores previous versions of itself as well; if something goes wrong and you want to revert back to an earlier version, this could be useful information. You can check out how many old versions of bash there are using the following command: ls -la /var/db/receipts/. /home/username/.bash* You’ll notice that there might be tens or even hundreds of old versions.

Limit the Contents of Your .bash_history File

If you want to limit the contents of your .bash_history file, you can do so by using the HISTFILESIZE and HISTSIZE variables. By default, the value of these variables is 500, but you can change them to whatever you want. For example, if you wanted to limit your history to only the last 100 commands, you would type export HISTFILESIZE=100.

If you wanted to limit the number of commands displayed when you use the history command, you would type export HISTSIZE=100. There are also a few other things that you can do to clear your bash history. You could simply open up a new terminal window and log in again, which will overwrite any of the commands in your current terminal session with those that are typed in this new terminal window. Alternatively, instead of logging out and logging back in, you could just close all terminals on the system with Ctrl + C then open a new one up again.

Delete Specific Lines From a Bash History File

If you want to delete specific lines from your bash history, you can do so by using the history command. First, find the line number of the command you want to delete by running the history command with no arguments.

Then, use the -d option followed by the line number to delete that specific line. For example, if I wanted to delete line number 100 from my history, I would run history -d 100. If you want to delete multiple lines at once, you can do so by providing a range of line numbers separated by commas. For example, history -d 5,10 would delete lines 5 through 10 from your history.

 Remove Entire Lines From a Bash History File

There are a few ways to clear your bash history, but the most effective way is to remove entire lines from the bash history file. This can be done by using the history command with the -d option. For example, if you wanted to delete line 100 from your bash history, you would use the following command:

`history -d 100` Remove Specific Items From a Bash History File: The second and more complicated method of clearing your bash history is removing specific items. To do this, you need to know the exact position in the bash history that needs to be removed. You can find this information by running the following command:

Continuation (six+ sentences): `history grep ‘pattern’ awk ‘{print $3}’` This will output only the third column (the item number) of each line that matches what you’re looking for, so make sure there are no spaces before or after your pattern! If there are any spaces within the pattern then make sure they’re escaped with backslashes as well!

Delete Entire Lines From a Bash History File

Deleting your entire bash history is a bit more complicated than just running `history -c`. First, you need to find your bash history file. This is usually located in your home directory, and is typically called `.bash_history`. Once you’ve found the file, open it in a text editor and delete everything. Save the file and exit. Now, when you run `history`, you should see that your bash history is empty. Congratulations! You’ve successfully cleared your bash history.

Add Lines to a Blocked Line List

  1. You can use the history command to view your entire bash history.
  2. To clear your entire bash history, use the clear or clr command.
  3. You can also use the erase command to delete specific lines from your history.
  4. If you want to prevent a command from being added to your history, you can use the HISTCONTROL variable.
  5. You can also use the ignorespace and ignoredups options to prevent commands with leading spaces or duplicate commands from being added to your history. 6. Alternatively, you can use the HISTIGNORE variable to specify which types of commands will not be saved in your history file.
  6. The following example blocks out all of the commands beginning with cd (cd ls cd ..) so that they are not saved in my history: export HISTIGNORE=cd
  7. Using the export command assigns the specified value to a shell variable.
  8. The last option is adding these lines to ~/.bashrc so that it applies on future logins as well: export HISTIGNORE=cd && echo ‘export HISTIGNORE=cd >> ~/.bashrc’ echo Command to add line to ~/.bashrc failed ! # A newline would have helped!

 Save Time and Memory by Limiting What Gets Saved

You probably know that you can clear your bash history by running `history -c`. But did you know that you can limit what gets saved in the first place? This can be useful if, for example, you want to keep certain commands secret or if you want to save time and memory by not saving unnecessary data. To do this, just add one of these three options when executing a command:

This will prevent the last $NUMBER of commands from being saved into bash history


echo hi > myfile && ls *.txt && echo bye >> myfile This command will create an empty file called myfile with hi inside it, list all

.txt files in the current directory and then append bye to the end of myfile. If we run `history` at this point we’ll see that only the first two lines are saved because our $HISTTIMEOUT variable is set to 10. When using an interval other than 0 (the default), we need to export it before appending our command. If we had used `unset HISTTIMEOUT` instead of setting $HISTTIMEOUT=10, nothing would have been saved! It’s worth noting that any command executed after the variable has been exported will use its value. In other words, even if our terminal was closed before we ran `history`, the previous ten commands would still be shown on startup.

Keep an Archive of Commands for Reference

It can be helpful to keep an archive of the commands you’ve run in bash. This way, if you need to reference a command later, you can easily find it. To do this, you can use the history command. This will print out a list of all the commands you’ve run in your current session. If you want to save this list to a file, you can use the > operator.

For example, if you wanted to save your history to a file called bash_history.txt, you would run the following command: history > bash_history.txt. Now that we have our log saved to a text file, we can go ahead and clear out our bash history. To clear out your bash history completely and start fresh, you can execute the following command: history -c && echo . Now when you type bash at the prompt and hit enter, nothing will happen because there are no old commands left for bash to execute.

The -c flag clears everything from your terminal’s memory (this includes both input and output), so make sure that’s what you want before executing this command!

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