Let’s Delete An Entry In Your Bash History

In today’s article, we’re going to learn how to delete an entry in your ‘bash’ history. It’s a useful skill to have, for any number of reasons. It’s not all that difficult and this shouldn’t be a very long article. Read on, my dear readers! Even a long-term Linux user might learn something – but I make no promises!

I’ve previously covered how to remove duplicates from your bash history. It may be worth checking that article out, as most of you are going to be using bash. Sure, there are other shells, but bash is the most common on desktops and servers. So, we might as well learn with bash.

If you don’t know, bash is both a language and an application. Unless otherwise specified, you’re almost certainly using bash when you open a terminal or TTY. 

When you enter a command in the terminal or TTY, it’s saved to your bash history. In fact, it’s saved to the hidden file ~/.bash_history. If you so wanted, you could just open the .bash_history file with a text editor and remove lines as you wished. That works just fine.

However, in this article we’ll be using the ‘history’ command. It’s a handy command, useful for recalling previously entered commands and managing those stored commands. I guess this is really more an article about performing some very basic tasks with the history command. Like I said, it’s good for you to know this sort of stuff – especially as a Linux beginner.

Delete An Entry In Your Bash History:

This article requires an open terminal, like many other articles on this site. If you don’t know how to open the terminal, you can do so with your keyboard – just press CTRL + ALT + T and your default terminal should open right up and be ready for use!

So, with your handy-dandy freshly-cracked-open terminal, let’s just display your bash history. You’re going to do that with just the following command:

You’ll notice that every stored command from your bash history is assigned a number that’s shown on the left (or right, if you use a RTL language). Well, that’s how you delete it. You use that number in the following command:

You can use that command to delete an entry in your bash history, and you can do so as often as you’d like. While you’re there, you can also just plain clear your entire bash history with this command:

That will clear all of your bash history – more or less. Your current session may have not been written to the history at the time you issued that command. It might not be saved until you close the terminal instance. This makes it slightly more complicated to make sure the history is truly empty. However, it’s definitely close enough.

Anyhow, you might want to delete your bash history to remove commands that you’ve memorized. You might want to remove commands that didn’t work. If there are sensitive commands in your bash history, this is a way to remove them, surgically or en masse. There are all sorts of reasons why you might want to go through your bash history to delete past commands – and now you can!

Closure:

Yay! It’s another back-to-basics kind of article. In this one, we learn how to delete an entry in your bash history file. In some cases, it may be easier for you to just do so with a GUI and a GUI text editor. You don’t even need ‘sudo’ to make the changes and removing a lot of entries might be faster with a graphical application. Just remove the lines you don’t want showing up in the history any longer.

Also, I should mention somewhere that you can see the history by just pressing the up arrow, but I suspect folks will already know that. ‘Snot the best way to go about managing them, but you can see and select them, running them again as you wish.

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Find Out Which Shell You’re Using

Today’s article is going to teach you how to find out which shell you’re using. Knowing which shell you’re using is important if you’re using an unfamiliar system. Most of the time, it’s something you’d already know, but once in a while you might need to find out which shell you’re using.

As you’re visiting this site, it’s fairly safe to assume you’re using Linux (or at least interested in Linux). In that case, you’re quite likely using Bash. Bash is the most common, from my observations.

If you’re curious, Bash is a replacement for Bourne Shell – and is ‘Bourne Again SHell’. It has existed, thanks to the Brian Fox and the GNU Project, since the late eighties. It’s pretty ubiquitous, pretty stable, and pretty feature complete.

While Bash is the most common, it’s certainly not alone in the field of shell options. There are other shells, from ZSH to Fish, or from Dash to Nushell. In some distros, you might find one of them installed by default, but it’s usually going to be Bash.

So, odds are pretty good that you will already know if you’re using something other than Bash. After all, you’d likely have been the person who installed the alternative. Still, there are a couple of commands you can use when you want to figure out which shell you’re using, for when you do need to know.

Find Out Which Shell You’re Using:

This article requires an open terminal, like many other articles on this site. If you don’t know how to open the terminal, you can do so with your keyboard – just press CTRL + ALT + T and your default terminal should open.

On the off-chance that you don’t know what a shell is, Wikipedia describes the shell as:

A Unix shell is a command-line interpreter or shell that provides a command line user interface for Unix-like operating systems. The shell is both an interactive command language and a scripting language, and is used by the operating system to control the execution of the system using shell scripts.

And now, with your terminal emulator open, let’s go about finding out which shell you’re using. 

The first command you can try would be:

You can also use the echo command in a different way. It’s even a bit more clear with this command:

You can also use ‘ps’ which takes snapshots of current processes:

There are certainly other ways to find out which shell you’re using, but those are a few ways that are easy enough. If you have other ways, please feel free to leave them as a comment.

Oh, and here’s a bonus… If you want to see which shells are installed on your system, you can use the following command:

The output of this would look similar to this:

list of installed shells
This is the defaults from Lubuntu 20.04 LTS. Your output may vary, of course.

As I said, that’ll let you know which shells you have installed. In a future article, we might discuss how to change your default shell – but that’s something I seldom bother with these days. Bash works and works well.

Closure:

Yup… There it is! Another article. Now that the year is up, I’m not sure what to look forward to as a goal. I highly doubt I’ll make it a full two years, but it could happen. We shall see…

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Automatically Logout Of Your Shell

For security reasons, you’ll possibly automatically logout of your user sessions. If you didn’t know, you can actually do that with your shell, in the terminal. There’s already a variable (TMOUT) just for this reason, should you want to add it as a layer of security.

Basically, for today, we’re going to set it up so that it automatically logs inactive users out of their shell session. It doesn’t log you out of your complete user session, it just logs you out of your shell – after a set period of activity. It even closes the open terminal windows when it does so.

So, depending on the interval you use, you can set it up to log you out of your shell instances after just a few minutes of inactivity. If you have nosy neighbors, like people physically near your computer, it can be a nice way to make sure things are all locked before you head off to the bathroom.

It’s useful for that sort of stuff. It’s just an added layer of security. I think that it is a pretty handy feature. I’ll explain how to enable it on a user-by-user basis and how to make it system-wide, giving you a choice. It’s actually pretty easy, so read on!

Automatically Logout Of Your Shell:

Like most good things in the Linux world, you’ll need an open terminal to take advantage of this article. If you don’t know how to open the terminal, you can do so with your keyboard – just press CTRL + ALT + T and your default terminal should open.

Both of these ways are pretty simple, in each case you add some text (using nano) to a profile file. The text in either case is the same. If you want to do it for just one user, the user you’re currently using, then run the following:

Add the following:

So, if you wanted it to be 10 minutes of inactivity before being logged out, you’d use TMOUT=600, because 600 seconds is 10 minutes. As you’re using nano, you can press CTRL + X, then Y, and then ENTER to save the file.

You’ll then force the profile to load, the command taking effect immediately, with this:

If you want to do it with the full system, the online guides will tell you to edit /etc/profile and that it’ll work if you do. My experiences are different and this is tested across multiple systems. You’ll be editing /etc/bash.bashrc, just like you did above but with sudo. (Using /etc/profile has not worked for me.)

Again, you add ‘TMOUT=600″ or however many seconds you want to wait. Personally? I scrolled to the bottom of the file, made a new line, and added the text that way. You could be all professional and add a comment indicating when and why you were there. I did nothing of the sort.

Unlike the first command, you’ll not be able to reload the second method (system-wide configuration) with ‘source ~/…’. As near as I can tell, you’ll have to restart the system for the changes to take place. If someone has a way to load it without rebooting, I’ll update the article. Please leave a comment if you do know of a way!

Closure:

There you have it, another article! This one tells you how to automatically logout from your shell. I’m not sure if it works for all shells, so feel free to test and see what sort of results you get. I’m pretty sure the 2nd option could be reloaded without rebooting, but I can’t think of which command. Which service would need restarting? I dunno?

Thanks for reading! If you want to help, or if the site has helped you, you can donate, register to help, write an article, or buy inexpensive hosting to start your own site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

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