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Environmental Variable Management

types of variables:

  • Environment variables are system-wide variables built into your system and interface that control the way your system looks, acts, and “feels” to the user, and they are inherited by any child shells or processes.
  • Shell variables are typically listed in lowercase and are only valid in the shell they are set in.

To view environmental variables:

env

To view all variables:

set

Change variable for session​

# HISTSIZE is a variable that controls the number of commands to remember
HISTSIZE=0

Change variable permanently​

Backup before modifying:

set > env.bkp

To make the change permanent, use the export command:

HISTSIZE=0
export HISTSIZE

Create user-defined variable​

NEW_VAR="some value"

echo $NEW_VAR
# some value

To delete a variable:

unset NEW_VAR