Managing your Command Line Like a Boss 😎
I’m no command line expert but I use it daily. For almost a year and a half I was using it in a way which I assume most of us would be using it.
- Run commands 🤴
- Run scripts 📜
- Git related stuff 📟
- Login to remote servers 🗄
- View files 📋
- Quick editing files 📠
But there is so much more that we can do with our terminals. Even with a few one time customizations you can do the following.
- Run startup scripts for shell ⛓
- Create aliases or shortcuts 🎏
- Store environment variables 🔑
- To give it a more personalized touch 🏯
Your tools are one of the most important factors which make you more efficient in your everyday work. You should definitely use more and more tools to up your game.
Whenever a user logs into a system a lot of background processes and initialization files are loaded into the system. A user has a home directory to create and store files that belongs to that user. But a lot of times a we also need to load some user specific configurations and processes to create its working environment which is determined by initialization files. These initialization files are defined by the user’s startup shell, which can vary depending on the operating system. The default initialization files in your home directory enable you to customize your working environment.
Important - The following blog is written for OS X. It might not work for other OS.
How to create your own initialization files ?
You don’t have to create your own initialization files. We get a number of different files located in hour user’s home directory.
~/.bash_aliases, etc. We can edit these files to add our initialization
scripts, environment variables, aliases, etc.
The only thing we need to know is when do we use which file? as each file serves a different purpose and is loaded in a slightly different way from other files. In order to understand that we need to know how these configuration files are loaded.
Types of shells and How they are loaded ?
Login Shell - A Login shell is started after a successful login, using
/bin/login, by reading the
/etc/passwd file. Login shell is the first process that executes
under our user ID when we log in to a session.
When Bash is invoked as a Login shell;
- Login process calls
/etc/profilecalls the scripts in
- Login process calls one of
Non Login Shell - A Non login shell is started by a program without a login. In this case, the program just passes the name of the shell executable. For example, for a Bash shell it will be simply bash.
When bash is invoked as a Non login shell;
- Non-login process(shell) calls
In OS X, Terminal by default runs a login shell every time Sourcing a file (by typing either
.filename at the command line), the lines of code in the file are executed as if they were printed at the command line.
When to use .bash_profile ?
.bash_profile should simply source your
.bashrc so you don’t have to repeat configurations in different files.
It can also contain stuff(commands, env variables, etc) that you want to run during the startup of a login shell.
# Add stuff here which you want to run when a new login shell(session) starts # It should load .bashrc file if [ -f ~/.bashrc ]; then source ~/.bashrc fi
When to use .bashrc ?
.bashrc should source your
.bash_aliases and contain stuff that you want to
run during the startup of a non login shell.
# Add stuff here which you want to run when a new non-login login shell starts # It should now output anything # Loads .profile if [ -f ~/.profile ]; then source ~/.profile fi # Loads .bash_aliases if [ -f ~/.bash_aliases ]; then source ~/.bash_aliases fi
When to use .bash_aliases ?
You should put all your bash alias definitions into a separate file like
~/.bash_aliases, instead of
adding them in the
~/.bash_profile file directly.
#.bash_aliases alias update='sudo -- sh -c "/root/bin/chk_disk && dnf update' alias ec2-prod='ssh email@example.com -i /path/to/special/privatekey/amazon.pem' alias check-brew='brew upgrade && brew update && brew cleanup -s' # EOF
Now you can type
check-brew in your shell and it will run the corresponding command(s) defined above.
> check-brew ... upgrading brew ... updating brew packages ... cleanup brew >
When to use .profile ?
.profile should contain all the env variables and you can also modify the path variable here.
# Set Path Variable here export PATH="$HOME/.cargo/bin:$PATH" # nvm initialization should also come here # set variable only for current shell NODE_ENV="development" # set it for current shell and all processes started from current shell export NODE_CONFIG_ENV="local" # EOF
Bash only reads the first one out of three files (.bash_profile, .profile, .bash_login). Meaning, if you have a .bash_login, then both .profile and .bash_profile will be mysteriously ignored. So make sure you don’t have a .bash_login file.
|.bash_profile||loads login shell stuff, calls .bashrc file|
|.bash_aliases||command aliases and shortcuts|
|.bashrc||loads .profile and loads .bash_profile and non login shell stuff|
|.profile||env variables, path variables|