In the command line, a shell script is an executable file that contains a set of instructions that the shell will execute. Its main purpose is to reduce a set of instructions (or commands) in just one file. Also it can handle some logic because it’s a programming language.
How to create it
Create the file:
$ touch myscript.sh
Add a shebang at the start of the file. The Shebang line is responsible for letting the command interpreter know which interpreter the shell script will be run with:
$ echo "#!/bin/bash" > myscript.sh # or $ your-desired-editor myscript.sh # write at the first line #!/bin/bash
Add some commands:
$ echo "echo Hello World!" >> myscript.sh
Give the file execution mode:
$ chmod +x myscript.sh
$ ./myscript.sh Hello World!
More info about shell-scripting can be found here