How to import a variable from another script?

command-line bash scripts environment-variables

33,804

Solution 1

First of all, be aware that var and VAR are different variables.

To answer your question the . command is not bash-specific:

# a.sh
num=42

# b.sh
. ./a.sh
echo $num

The variables in "a" do not need to be exported.

http://www.gnu.org/software/bash/manual/bashref.html#Bourne-Shell-Builtins

Solution 2

Environment variables are only inherited from parent to child and not the other way round. In your example, b.sh calls a.sh, so a runs as a child of b. When a.sh exports var, it won't be seen by b.sh. Amend the logic so that the parent process exports the variable, e.g.

a.sh:

echo In a.sh...
VAR="test"
export VAR
./b.sh

b.sh:

echo In b.sh...
echo $VAR

33,804

Eero Aaltonen

Updated on September 18, 2022

Comments

Eero Aaltonen over 1 year
I want to get a variable from another script, as demonstrated in this question on Stack Overflow:

How to reference a file for variables in a bash script

However, the answer uses the source command which is only available in bash. I want to do this in a portable way.

I have also tried

a.sh
```
export VAR="foo"
echo "executing a"
```
b.sh
```
#!/bin/sh
./a.sh
echo $VAR
```
But of course that does not work either. How to do this?
Eero Aaltonen almost 11 years

Thank you and excuse my typo. I was pretty surprised with the difference between ./a.sh and . ./a.sh. Care to explain the difference?
Eero Aaltonen almost 11 years

Thank you, but I actually have sharedDefs.sh and two separate targets depending on it, so I need to have the dependencies this way.
fiatux almost 11 years

The dot command (. or source) evaluates the script in your current shell. Executing the script first spawns a subshell, and any environment changes in the subshell are lost when the subshell exits -- a child process cannot alter the environment of its parent.
fiatux almost 11 years

bash has a handy help builtin to access the manual for a specific command -- see help .