In my blog Write A Bash Script 101, I write about how to make a simple bash script from scratch. The purpose of this blog is to serve as a reference (or tool kit) of different bash commands, that you can use as you start creating new bash scripts, and to help open the door of endless possibilities of productivity the world of bash scripts has to offer.
I go over pushd and popd in this blog about alias's. Alias are a great way to basically write one line bash scripts, so I recommend checking it out if you are unfamiliar with bash alias's. Pushd and popd offer an alternative to cd that have a history you can pop backwards through. Although, it's doesn't have to completely replace cd.
Say your in
~/Downloads directory and you
pushd ~/Documents/projects/my-project and then you want to go back to just the projects directory. If you use
popd then it will take you back to the Downloads directory, so if you want to go to projects directory you have 2 choices:
pushd ~/Documents/projectsWe have to use an absolute path here because we don't have a way to just move up a directory. Pro you keep the pushd history going. Con you have to type a little more.
cd ..You move out of the directory into the parent directory. Pro easy to type. Con you break the
pushdhistory chain. > Note: If you have an alias for the projects directory because you use it so often, when you're in your actual project folder you can just type the alias for that projects directory to bring you back and keep the pushd history chain going without typing the whole absolute path.
If you're in your projects directory and you
cd my-project/ or
pushd my-project you are typing a relative path. A relative path is a path that is relative to the current directory you are in.
An absolute path would look like;
cd ~/Documents/projects/my-project/ or
pushd ~/Documents/projects/my-project/. This will take you to you my-projects directory no matter where you are in your filesystem, which can be really powerful when used in bash scripts.
Variables are in many coding languages. In bash variables are usually named in all caps and a $ is called in front to let bash know it's a variable.
Typical syntax for declaring a variable:
Now if you were to save that to your .bashrc file and reload your terminal and type in
echo "$NAME" it should return "Jimmy McBride".
Bash comes with a few variables already that you can use. Here are some I use the most:
- $PATH: returns to you all the paths to bin folders you can use to put your bash scripts in.
- $HOME: returns to you your home route. Usually looks like
- $USERNAME: returns your username.
- $PWD: returns your Present Working Directory
- $1, $2, etc: When you type the name of you bash script it runs the file. You can also type in extra arguments. If you do $1 becomes the first argument you typed after the name of your script and so on.
File name: new-project
#!/bin/bash # Push to projects directory with an absolute path pushd ~/Documents/projects # Run create-react-app in projects directory yarn create react-app "$1" # Move inside the new project folder with a relative path pushd "$1" # Open project in VS Code code . # Start server yarn start
Here we can type
new-project my-project and it will create a new react app with the name of our first argument ('my-project' in this case) and then move inside that directory, open the project in VS Code and start the server.
Since we used an absolute path at the beginning of our script, it will take us to the projects directory from anywhere in our file system, where we use this command and run create-react-app in the appropriate directory. We only need to use a relative path to move inside the project directory because we are already in the folder we need to be in.
Syntax for moving files:
mv <target> <destination> # or mv <target> <target> <destination> # Examples # Moves file1 into folder1 mv file1 folder1 # Moves file1 and file2 into folder1 mv file1 file2 folder1 # Moves folder1 and file1 into folder2 mv folder1 file2 folder1
The syntax for copying files and folders is:
cp <target> <destination> # Copies file1 into folder1 cp file1 folder1 # If you want to copy an empty folder somewhere: cp folder1 folder2 # If the folder is not empty, you want to copy it recursively: cp -r folder1 folder2
These are just a few of the many tools bash has to offer when writing your scripts. I've found that I see myself using these commands the most. As I learn more and get better at writing bash script I will update this blog so be sure to add it to your reading list! What are some of your favorite bash commands you use? Would love to here your thoughts and opinions in the comments below!