What is shell variable and environment variable?

What is shell variable and environment variable?

Environment variables – Variables that are exported to all processes spawned by the shell. Their settings can be seen with the env command. A subset of environment variables, such as PATH, affects the behavior of the shell itself. Shell (local) variables – Variables that affect only the current shell.

How do I set environment variables in Bash shell?

The easiest way to set environment variables in Bash is to use the “export” keyword followed by the variable name, an equal sign and the value to be assigned to the environment variable.

What is the difference between a variable and an environment variable?

Environment variables. An environment variable is a shell variable which has been exported. This means that it will be visible as a variable, not only in the shell session that created it, but also for any process (not just shells) that are started from that session.

Can a shell variable be exported to an environment variable?

If a change is made to a shell variable, it must be explicitly “exported” to the corresponding environment variable in order for any forked subprocesses to see the change. Recall that shell variables are local to the shell in which they were defined.

What’s the difference between set and env in Bash?

Bash seems to differentiate between variables which have been exported and those which have not. set sees the variable but env does not. set sees both variables but env sees only the exported variable. I know that set is a bash builtin and env is not.

What’s the difference between$ Bash and$ shell?

Environment variables such as $SHELL are valid systemwide. In a current Bash shell, $BASH points to the execution path of bash, whereas $SHELL points to the shell defined as default (which may be of the same value). For an explanation of environment variables see Environment Variables in Ubuntu Help.