"Can soneone explane me what is variable in Linux ?"
A variable is a name that contains some useful information. An example of a variable is PATH which contains the names of the directories where Linux looks for the commands that you execute. You can display any variable with the echo command:
You can create a variable with the export command:
Variables do not have to be capitalized but most people do that to distinguish variables from commands.
A command starts a program. echo is a program, so are mozilla, export, mount, and thousands of others.
Commands are usually small letters to distinguish them from variables.
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