Linux bash call functions

The trick to making a bash script callable from the command line with specific function names is the "$@" at the end. Without it, defining functions in a script does nothing useful — you’d have to source the script and call them manually. This pattern makes scripts behave like a proper CLI with named subcommands.

• Create an empty file with .sh extension

$ touch test.sh

• Use your favourite editor add a method to the file

$ vi test.sh

#!/bin/bash

function no_input(){
    echo "hello world"
}

"$@"

”$@” is what that makes the script file (.sh) be able to call methods

• Make file executable

$ chmod u+x test.sh

• Call method

$ ./test.sh no_input
hello world

• Add another method to file

$ vi test.sh

#!/bin/bash

function with_input(){
   echo "hello $1 how are you?"
}

function no_input(){
    echo "hello world"
}

"$@"

• Call new method with input argument

$ /test.sh with_input 'User'
  hello User how are you?