Learning Bash

Today I’ve decided to plunge a little deeper into the bash world.

mkdir hammerTime
chmod 500 hammerTime
cd hammerTime
touch this

Interactive and non-interactive modes

• Interactive: Shell commands such as; ls, cd, mkdir, rm.

• Non-interactive: Where the shell reads commands from a .bash file or a pipe and executes them.

Useful Commands:

• touch - to create a script file
• chmod +x "<file name>" - to create an executable file
• man - to query a bash command
• which - to search for a directory
• cat or less - to read a .txt files
• ls - to print current working directory
• cd - to change current working directory
• pwd - print working directory
• echo - to print

Non-interactive

• To run a script from local directory: ./<file name>.bash
• In script files you can basically code processes to automate routines that you do on your system. Scripts can be made to input/output data to certain programmes, create files, pull data .etc.
• In this this script you can create both global and local variables to be used, however many global variables already exist in bash.
• For global variables $<CAPITALS> syntax is used.
• Global variables: $PWD $CD $MKDIR $USER $HOME

Pipelines:

Piping in bash seems useful, it’s a way of directing data around programmes on one command line. The syntax pipe | is used for this. Similarly > can be used for redirecting output and < can be used for redirecting input.

Right now, I can’t see much personal use for writing non-interactive script, but can see the use of learning some key interactive commands.

In order to get a better appreciation of non-interactive scripts, I think it may help to see how a more experienced developer uses bash scripting.