denilsonpy / bash

Bash script

Bash

Bourne-Again SHell

What is a Script?

A shell script is a file containing commands for the shell.

A Bash script is simply a file containing commands for the Bash shell.

Why use scirpts?

Scripts Allow Automation

What is shell?

The shell is command-line interpreter that makes it easy for you to issue commands to your operating system

Files permissions

"Permissions Calculator"

1234567890

1 -> - or d -> - = file and d = directory

file owner

2 -> - or r -> read permission -> - or r -> i - no and r - yes
3 -> - or w -> write permission -> - or w -> i - no and w - yes
4 -> - or x -> execute permission -> - or x -> i - no and x - yes

files group

5 -> - or r -> read permission -> - or r -> i - no and r - yes
6 -> - or w -> write permission -> - or w -> i - no and w - yes
7 -> - or x -> execute permission -> - or x -> i - no and x - yes

other users

8 -> - or r -> read permission -> - or r -> i - no and r - yes
9 -> - or w -> write permission -> - or w -> i - no and w - yes
0 -> - or x -> execute permission -> - or x -> i - no and x - yes

PATH

The PATH variable tells the shell where to search for executable files

We can add folders to our PATH variable by modifying the .profile file

Try to avoid giving your scripts names that may conflict with another command on the system

Sample:

export PATH="$PATH:$HOME/github/bash_course/scripts"

Types of shell parameters:

• Variables
• Positional parameters
• Special parameters

Shell variables

• Bourne Shell Variables

  • Bourne shell (created by Stephen Bourne 1979)
  • 10 in total

• Bash Shell Variables

  • Bash shell (based on the bourne shell)
  • Bourne Again SHell (BASH)
  • Around 95 in total