Bash Script

1. Shortcut command

1.1. Simple alias

alias agi='sudo apt-get install'

Add line to end of ~/.bashrc file.

1.2. Start a script

#!/bin/bash
echo "changing directory.."
cd ~/project/wayneyee.github.io
echo "starting jekyll.."
bundle exec jekyll serve

Add to $home/bin.

Make file executable sudo chmod +x filename.

Add line to end of ~/.bashrc file.

export PATH=$PATH:$HOME/bin

• export make variable available for children of this terminal
• PATH work on variable named PATH
• = assign it a new value, which is
• $PATH the old value
• : a separator
• $HOME/bin and your newly created bin directory

Start using the new bashrc file:

source ~/.bashrc

1.3. Examples

Add to $home/bin.

2. Write to File

# overwrite
output > filename 
# append
output >> filename 

echo "this is a line" > file.txt
echo "this is a line" | tee file.txt
echo "this is a line" | tee -a file.txt

cat << EOF > file.txt
The current working directory is: $PWD
EOF

3. Bash Script Basics

Bash Guide for Beginners

Script starts with a “shebang” for the shell to decide which interpreter to run the script for example bash, tsch, zsh, Perl, Python etc.

#!/bin/bash
#!/usr/bin/env python3  #!/path/to/interpreter

To set the script executable run chmod +x scriptname.

• + add permission
• x executable

3.1. Variables

#!/bin/bash
SOURCEDIR=/home/user/Documents/
echo "path" $SOURCEDIR

3.2. Taking input

#!/bin/bash
echo $1

#!/bin/bash
echo -e "Please enter your name: "
read name
echo "Nice to meet you $name"