The Simple Stuff

Every so often I will stumble across a new command that is incredibly useful or just really cool.  It is in those moments I realize how little I actually know about this operating system and how incredibly powerful it actually is.   Linux is easily molded into whatever we need it to be.  If you break it down and learn the tools used to model it you can literally get it to do pretty much anything.  Obviously there are going to be computational limitations, but within those limits the capabilities are still quite amazing.

So let’s start with a simple command. 

[myprompt]$ ls

The ls command allows a user to list the contents of a directory.  A simple command by itself, but when coupled with other scripting commands you begin to create dynamic tools within scripts.

For instance let’s say the linux machine is used for maintaining characters.  Each character has configuration data associated with it.   We will give each character configuration a name in the form of <CharacterName>.chcfg

We have a program that creates deletes and stores these files in /Data/Characters directory.  Let’s say we have another program that needs to list all the characters.  This is one method:

#!/bin/bash

##Char list script

CHAR_CONF_DIR=/Data/Characters

MY_CHARACTERS=(  `ls ${ CHAR_CONF_DIR}\*.chcfg`   )

echo ${ MY_CHARACTERS[@]}

MY_CHARACTERS is a bash array.  The bash array just stores each individual .chcfg file within one variable. The ls command allowed us to easily access the .chcfg data and store it into the variable.  So now each time we add or remove a .chcfg file and run the script it will automatically update the MY_CHARACTERS variable without any modifications to the script.