Today lets learn about .bashrc file. If you have been using Linux for a while and particularly if you are beginning to get familiar with the Linux command line you will know that BASH is a Linux shell.
BASH stands for Bourne Again Shell. There are a number of different shells including csh, zsh, dash and korn.
A shell is an interpreter which can accept commands typed or entered by a user and run them to perform operations such as navigating around a file system, running programs and interacting with devices.
Many Debian based Linux distro’s such as Debian itself, Ubuntu and Linux Mint use DASH as a shell instead of BASH. DASH stands for Debian Almquist Shell. The DASH shell is very similar to BASH but it is a lot smaller than the BASH shell.
Regardless as to whether you are using BASH or DASH you will have a file called .bashrc. In fact you will have multiple .bashrc files.
Open a terminal window and type in the following command:
sudo find / -name .bashrc
When I run this command there are three results returned:
The /etc/skel/.bashrc file is copied into the home folder of any new users that are created on a system.
The /home/gary/.bashrc is the file used whenever the user gary opens a shell and the root file is used whenever root opens a shell.
What Is The .bashrc File ?
The .bashrc file is a shell script which is run every time a user opens a new shell.
For example open a terminal window and enter the following command:
Now within the same window enter this command:
Every time you open a terminal window the bashrc file is performed.
The .bashrc file is a good place therefore to run commands that you want to run every single time you open a shell.
As an example open the .bashrc file using nano as follows:
At the end of the file enter the following command:
echo "Hello $USER"
Save the file by pressing CTRL and O and then exit nano by pressing CTRL and X.
Within the terminal window run the following command:
The word “Hello” should be appear along with the username you are logged in as.
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Use Of Aliases
The .bashrc file is commonly used to set aliases to commonly used commands so that you don’t have to remember long commands.
Some people consider this a bad thing because you could forget how to use the real command when placed on a machine where your own particular .bashrc file doesn’t exist.
The truth is however that all of the commands are readily available online and in the man pages so I see adding aliases as a positive rather than a negative.
If you look at the default .bashrc file in a distribution such as Ubuntu or Mint you will see some aliases already set up.
alias ll='ls -alF' alias la='ls -A' alias l='ls -CF'
The ls command is used to list the files and directories in the file system.
The -alF means that you will see a file listing show all files including hidden files which are preceded with a dot. The file listing will include the author’s name and each file type will be classified.
The -A switch simply lists all files and directories but it omits the .. file.
Finally the -CF lists entries by column along with their classification.
Now you could at any time enter any of these commands direct into a terminal:
ls -alF ls -A ls-CF
As an alias has been set in the .bashrc file you can simply run the alias as follows:
ll la l
If you find yourself running a command regularly and it is a relatively long command it might be worth adding your own alias to the .bashrc file.
The format for alias is as follows:
alias new_command_name = command_to_run
Basically you specify the alias command and then give the alias a name. You then specify the command you wish to run after the equals sign.
alias up='cd ..'
The above command lets you go up a directory simply by entering up.
The .bashrc file is a very powerful tool and is a great way to customize your Linux shell. Used in the correct way you will increase your productivity ten fold.