How do i use bash variables between shell scripts?

vaquitasos

Using bash variables between shell scripts is the area of Variable Scope, this is similar to other programming languages. Variable scope determines where in the scripts a defined variable can be used.

To demonstrate this, with two scripts, one script calls another script. The second script tries to use a variable from the first script. Let's see the results of this.

First script. that calls the second script.

#!/bin/bash
Myvar=pineapple
echo "My favourite fruit is $Myvar"
./mysecond.sh

Second script That tries to use the variable $Myvar

#!/bin/bash
echo "But Barney does not like $Myvar"

Run the first script.

$ ./myfirst.sh 
My favourite fruit is pineapple
But Barney does not like

The result is: the second script runs but does not know what the $Myvar variable is, so does not print it.

In order to have the second script know about the $Myvar the scope can be extended to the second script by using the export command.

Edit the first script to run the export command.

#!/bin/bash
Myvar=pineapple
export Myvar
echo "My favourite fruit is $Myvar"
./mysecond.sh

Run the first script again.

$ ./myfirst.sh 
My favourite fruit is pineapple
But Barney does not like pineapple

Now the second script knows what the $Myvar is set to.