Successfully Save The Day With Bash History Commands

Yogesh Oka    

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In many cases, you’ll get thousands of history lines, and you’ll have a hard time scrolling through them. But read on, and you’ll learn to customize the output in the way you want in the following steps. In this article, we will explain how to effectively use and customize the bash command history to get the most out of its features. The bash shell is the default command line environment available in most Linux distributions. Similar to all shell environments, it keeps a record of commands that have been executed previously by the user.

bash history

It enables you to recall and reuse the stored record in an efficient way to get the best out of saving feature. Not only this, but you can also customize and control the bash command output in the way you want. H Remove a trailing pathname component, leaving only the head.

Like most Unix shells, it supports filename globbing , piping, here documents, command substitution, variables, and control structures for condition-testing and iteration. The keywords, syntax, dynamically scoped Learn about the JavaScript String Methods & How to Use Them variables and other basic features of the language are all copied from sh. Other features, e.g., history, are copied from csh and ksh. Bash is a POSIX-compliant shell, but with a number of extensions.

#Working with Bash history: The basics

During a terminal session, you’ll likely be repeating some commands often, and typing variations on those commands even more frequently. While typing each command repeatedly can be good practice in the beginning, at some point, it crosses the line into being disruptive and an annoyance. Look into how one might correlate bash and alternate shell commands to events in Linux audit logs. An external command called bashbug reports Bash shell bugs. When the command is invoked, it brings up the user’s default editor with a form to fill in.

  • S/old/new/
    Substitute new for the first occurrence of old in the event line.
  • & Repeat the previous substitution (made with s/old/new/ ).
  • Only ‘\’ and ”’ can be used to escape the history expansion character.
  • The information we covered here should help you handle most of the common bash history use cases you’ll encounter.
  • All three of the previous expansion commands are examples of designators.

@oneindelijk history only writes the current shell’s in-memory history to the history file. A cron job would presumably not have access to the history of other running shells. If done correctly, bash histories should be appended to the file for all sessions, even in the event of concurrent bash sessions. $ event designator saves you a lot of time rerunning commands with lengthy or complicated arguments. Rerunning commands from history without retyping everything is fun, right?

Great Linux resources

The first parameter is HISTFILESIZE, which dictates how many commands are stored in the history file in total. The second parameter, HISTSIZE, dictates how many commands are stored in a given session. By increasing these values in the .bashrc file, you can increase the number of commands stored in the bash history. This should output a numbered list of all past commands entered into the system, in chronological order. If you wish to expand the amount of commands stored in the bash history, you can do so by modifying the .bashrc file. This file dictates how a given user’s bash profile operates, including how bash history is stored.

bash history

It will list the entire history for a specific user from the history file stored specifically for that user. You will see all the commands starting with a number allocated to each of them. It will list the older commands at the top starting with number 1 and the newer commands at the bottom. Bash also allows you to run a new command, but use arguments from previous commands in your history. This can help you quickly reuse long or complicated arguments without having to retype them. This command clears their history on each log on and removes the problem of picking up a previously run command.

For that reason, the history function in each shell is unique, so what you use in Bash may not work in Tcsh or Fish or Dash, and what you use in those may not work in Bash. In some cases, knowing what Bash can do may inspire users of other shells to create interesting hacks to clone Bash behavior, and it may unlock Bash features that you never knew existed. That is, it’s an old shell with an even older ancestor , but it also has a great history command that surpasses all other shell history interfaces based on its number of features. The Bash version of history allows for reverse searches, quick recall, rewriting history, and more. Bash also allows you to rerun the previous command and specify something that should be changed. This can be useful for correcting a typo in a command.

A Complete Guide to Linux Bash History

When working in a Linux command-line interface , you may find yourself wondering exactly what commands you ran during the course of your workflow. Fortunately, most Linux operating systems store your commands in a bash history file, which is a stored list of all commands a given user has entered into the system. By reviewing this list, users can troubleshoot input errors or mistakes made while performing command-line operations. In this article, we will explore how to review bash histories and discuss the importance of the information contained within. This means you can set a reasonable cap for the size of history in memory for the current session, and have an even larger history saved to disk that you can examine at a later time.

But only when the shell exits or if the commands history -a or history -w are executed. If any of the above fail, no history is stored in memory and consequently no history could or will be written to disk. If you configure to save after each command, then consider the implications of having multiple bash running at same time. @young_souvlaki I expect your man history is for a library; at least, that’s what the only such man page I have available says at the top. It would be unusual for a library to document command-line options of other software, but help history will show applicable Bash documentation. This feature is helpful if you remember the beginning of the command’s name, so you don’t have to view and search the Bash history.

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T Remove all leading pathname components, leaving the tail. R Remove a trailing suffix of the form ‘.suffix’, leaving the basename. Q Quote the substituted words, escaping further substitutions. X Quote the substituted words as with ‘q’, but break into words at
spaces, tabs, and newlines.

How to manage your Linux command history

However, as you become comfortable using modifiers and the other bash history expansion tools, you can greatly expand your capabilities and productivity on the command line. You could just as easily keep the full absolute path name and this command would work correctly in this instance. However, there may be other times when this isn’t true.

You’ve seen how to view the Bash history and control the number of commands to view. But what if you like to find a particular command in your Bash history and don’t remember exactly what it was? Piping other commands, like grep, to the history command will do the trick. Next, run the history command below to view the last 10 commands recorded in the Bash history. Replace 10 with the number of lines you like to display. Make sure your ad blocker is disabled.In this tutorial, you’ll learn some of the most helpful Bash history commands and never lose track of your commands’ executions.

With that, you’ve adjusted how your shell handles your command history. You can now get some practice finding your previous commands with the history command. By default, bash writes its history at the end of each session, overwriting the existing file with an updated version. This means that if you are logged in with multiple bash sessions, only the last one to exit will have its history saved.

Each user account has its own history file with a separate command history. A colon-separated list of values controlling how commands are saved on the history list. If the list of values includes ignorespace, lines which begin with a space character are not saved in the history list.