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Bash variable inheritances cheat sheet

Just a quick cheat sheet about how variables in Bash get inherited.

Result

Here’s the result of a call to outer.sh (see below):

Call
-------
From Outer (export):    yes
From Outer (no export):
From Inner (export):
From Inner (no export):

Source
-------
From Outer (export):    yes
From Outer (no export): yes
From Inner (export):    yes
From Inner (no export): yes

Test

The test consists of two files: outer.sh and inner.sh.

outer.sh is called by the user and internally calls inner.sh – once directly and once with source.

Contents of outer.sh:

#!/bin/bash

export FROM_OUTER_EXPORT="yes"
FROM_OUTER_NO_EXPORT="yes"

echo "Call"
echo "-------"
./inner.sh
echo "From Inner (export):    $FROM_INNER_EXPORT"
echo "From Inner (no export): $FROM_INNER_NO_EXPORT"

echo 
echo "Source"
echo "-------"
source ./inner.sh
echo "From Inner (export):    $FROM_INNER_EXPORT"
echo "From Inner (no export): $FROM_INNER_NO_EXPORT"

Contents of inner.sh:

#!/bin/bash

echo "From Outer (export):    $FROM_OUTER_EXPORT"
echo "From Outer (no export): $FROM_OUTER_NO_EXPORT"

export FROM_INNER_EXPORT="yes"
FROM_INNER_NO_EXPORT="yes"

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