export command in Linux CLI - Step-by-Step Execution

Concept Flow - export command

Start shell session

↓

Define variable

↓

Use export command

↓

Variable added to environment

↓

Child processes inherit variable

↓

End

The export command marks a shell variable to be passed to child processes, making it part of the environment.

Execution Sample

Linux CLI

MYVAR=hello
export MYVAR
bash -c 'echo $MYVAR'

Defines a variable, exports it, then runs a child shell that prints the variable's value.

Execution Table

Step	Action	Variable State	Output
1	Define MYVAR=hello	MYVAR=hello (shell only)
2	Run export MYVAR	MYVAR=hello (environment)
3	Run child shell: bash -c 'echo $MYVAR'	Child shell inherits MYVAR=hello	hello
4	End	No change

💡 Child shell prints 'hello' because MYVAR was exported to environment.

Variable Tracker

Variable	Start	After export	In child shell
MYVAR	undefined	hello (exported)	hello

Key Moments - 2 Insights

Why does the child shell print 'hello' only after export?

Because before export, MYVAR is only a shell variable, not in the environment. Export adds it to the environment so child shells can see it, as shown in execution_table step 3.

What happens if you define a variable but do not export it?

The variable stays local to the current shell and is not visible to child processes, so commands like 'bash -c' won't see it (see execution_table step 1 vs 3).

Visual Quiz - 3 Questions

Look at the execution table, what is the value of MYVAR in the child shell?

A hello

B undefined

C empty string

D MYVAR

💡 Hint

Check execution_table row 3 under Output and Variable State columns.

At which step does MYVAR become part of the environment?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at execution_table step 2 where export is run.

If you remove the export command, what will the child shell output be?

A hello

B MYVAR

C empty string

D error

💡 Hint

Refer to key_moments about variable visibility without export.

Concept Snapshot

export command:
- Marks a shell variable for environment export
- Makes variable visible to child processes
- Syntax: export VAR_NAME
- Without export, variable is local to current shell
- Useful for passing config to scripts or subshells

Full Transcript

The export command in Linux shell is used to make a variable part of the environment. When you define a variable like MYVAR=hello, it exists only in the current shell. Running export MYVAR adds it to the environment so child processes, like a new bash shell, can access it. This is why the child shell prints 'hello' when running 'bash -c echo $MYVAR'. Without export, the child shell would not see the variable and print nothing. Export is essential for passing variables to scripts or subshells.