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Table of Contents
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Understand the concept of a variable and how to do every process to create your own.
What is a variable?
A variable as its name implies is to store varied content in a memory location / space, instead of using numbers to make your call, we use tags / names! This makes it easier to make the call, isn't it? Shell variables can receive any content! from a simple string / text, numbers, output status of a command and return output.
When should we use a variable?
At any time! variables are cool to work with, let's suppose as an example i needed to call a specific directory 4 times! Would it be feasible for me to always type this manual directory? Wouldn't it be flawed if in the future I decided to change the directory itself? And if I forget to change any path is for sure fail! For this I use a variable to help me!
# Declaration DIRECTORY="/home/slackjeff/local_directory" # If directory does not exist, create. if [! -d "$DIRECTORY"]; then mkdir "$DIRECTORY" fi cd "$DIRECTORY" echo "I'm in the directory '$DIRECTORY'"
# HEREDOCUMENT text=$( cat << END Hi, welcome to my site, man! Here you will find everything but money. END ) # PRINT dialog --msgbox "$text" 0 0
Variable Types
In shell there are no variables of type (char, int, float, double). Here is all merciless string! Don't worry … Just schedule it.
Declaring a variable
In shell we don't need to declare variables! but get used to the way you call: D The order to declare a variable is:. Note that the variable name cannot contain any special characters like: '@ - | & * # $ \ /' among others, they cannot also start with numbers and have spaces … If your variable name contains spaces replace with _ 'underline', yes! underline can. Do not use - 'dash' that will not roll, it is a special character. After declaring a GOOD variable name you must enter the '=' sign and the value / content. Let's go to some examples:
CORRECT STATEMENTS
size_calca_42="Lie or use 42" name="Jefferson" _my_street="Pedro dos Santos" MyHomeNumber="1076552" CPF_AND_RG = "CPF: xxxxxxxx-xxxxxx.xx RG: y.yyy.yyyy"
WRONG statements
echo="Jeffa" **Works more is booked.** ls="Uoool" **Works more is booked** *Nom&="Paula" 1name="Fernanda" goat-street="Pedrino Nicolau" language=favorite="shell" MY YELLOW="this won't work"
Take care if you are beginner and making the wrong statement will not worka. The shell will complain, yes! he is a very angry guy with bad statements. Then it binds, without special characters, start numbers and spaces.
Sources
- Originally written by Slackjeff