Environment variables

So far we have only talked about variables that are local to a script. There are also system wide environment variables (env vars) which play a very important part of any Linux system. Here are a few, some of which the reader may already be aware of:

Variable

Role

HOME

user's home directory

PATH

directories which are searched for commands

PS1

command line prompt

HOSTNAME

hostname of the machine

SHELL

shell that is being used

USER

user of this session

EDITOR

text editor to use for crontab and other programs

HISTSIZE

number of commands that will be shown by the history command

TERM

type of command line terminal that is being used

Most of these are self-explanatory, however, I will mention ...

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