Bash for noobs

  Bash   Linux

Basic Bash commands

Selected basics

ls # List contents of directory
Add -1 to display results in a single column. Add -l to see more details. Add -a to show hidden files and folders. Use ls "/[dir_name]" to set absolute path and navigate there.
pwd # Print working directory 
mv # Move directory or rename 
touch file.txt # Create file.txt in current folder
rm # Remove file/directory (add -r to delete everything inside it i.e. recursively)
Get ranger (console file manager) to improve the entire navigation experience. When using ranger, you can use Shift + S to navigate to the current directory. Type exit after that to close the instance and return to ranger. Use Shift + Q to quit ranger. Consider adding alias r='. ranger' to your .bashrc file which will allow you to use ranger with r and let the shell follow ranger, so that when exiting with l, the current folder in ranger is also opened in your shell.

Refresh/reload profile

. ~/.bashrc

ln -s [target_path] [link_path]

# Example: Links the .ssh folder inside a WSL to the corresponding folder on Windows
# i.e. a shortcut at ~/.ssh will be created that, when opened, will show the contents of C:\Users\Kim\.ssh
ln -s /mnt/c/Users/Kim/.ssh ~/.ssh

Set a variable

echo "Please enter a bucket name: "; read bucket; export MYBUCKET=$bucket

Save variable to .bashrc

echo "export MYBUCKET=$MYBUCKET" >> ~/.bashrc

Download file

wget https://www.somewhere.com/file.zip

Unzip file

unzip file.zip -d ~/webapp1

Set & remove alias

alias # Show all
alias rm="rm -i" # Add alias
unalias rm # Remove alias

To set it permanently for all future bash sessions add such line to your .bashrc file in your $HOME directory.

To set it permanently, and system wide (all users, all processes) add set variable in /etc/environment.

Convert DOS file format to ISO, ASCI or 7bit

This should only be required when you do something silly such as creating text files in your WSL in Windows Explorer and then hope you can use them in the same way in Linux. Reference: https://linux.die.net/man/1/dos2unix (DOS/MAC to UNIX text file format converter).
sudo apt install dos2unix # Install dos2unix
dos2unix -c iso test.sh newtest.sh # Converts by creating new file

Viewing files

cat -n [file_name] [file_name] # Concatenate files with row numbers
less [file_name] # Scroll through file
head -5 [file_name] # Display first 5 rows of file
head -c 5 [file_name] # Display first 5 characters of file
tail -5 [file_name] # Display last 5 rows of file

Working with SSH

# List all added keys
ssh-add -l

# Generate a new key using ed25519 algorithm and adding your email as meta data
ssh-keygen -t ed25519 -C "[your_github_email@example.com]"

# Show fingerprint of a generated key
ssh-keygen -lf ~/.ssh/id_ed25519.pub

# Copy public key to server
ssh-copy-id -i ~/.ssh/[id_ed25519.pub] [username]@[ip]

# Example configuration to store in ~/.ssh/config 
Host [server_name]
    HostName [x.y.z.w or url]
    IdentityFile [~/.ssh/id_ed25519]
    IdentitiesOnly yes
    User [username]
    Port [port]

Bash scripts

Full update, upgrade and clean-up

#!/bin/bash
rm -rf /var/lib/dpkg/lock-frontend
rm -rf /var/lib/dpkg/lock
apt-get update
apt-get upgrade -y
apt-get dist-upgrade -y
apt-get autoremove -y
apt-get autoclean -y
echo 'Update, upgrade, and clean-up executed.'

Useful resources

General

  1. Online Bash Shell
  2. ShellCheck – shell script analysis tool
  3. TLDR pages/help for commands
  4. Awesome List of CLI/TUI programs

Specific topics

  1. How to use grep command in Linux/Unix with examples
  2. Bash Test Operators Cheat Sheet - Kapeli
  3. Oh My Posh - Prompt theme engine for any shell
    Add eval "$(oh-my-posh init bash --config ~/.poshthemes/catppuccin_macchiato.omp.json)" to .bashrc
  4. Ranger - Console file manager