Say you h​ave a bash script that looks like

​#!/bin/bash
SOME_VARIABLE=hello
some_program

where some_program ​is just some executable. Further this script is executed like

$ FOO=bar ./my_script.sh

Observation: the variable FOO=bar ​will make it to some_program ​whereas SOME_VARIABLE=hello ​will not.

To pass SOME_VARIABLE=hello to some_program turn on following flag in your script:

set -a

or put SOME_VARIABLE=hello on the same line as some_program in the script as shown below:

SOME_VARIABLE=hello some_program

It can be tested as follows

1. Create a file JavaEnvironmentVariables.java with this code
   
2. Compile this program by running
   ​$ javac JavaEnvironmentVariables.java
3. ​Write test script as follows
   #!/bin/bash

   SPAM=eggs

   java JavaEnvironmentVariables

4. Chmod755 the script and execute it
   $ FOO=bar ./my_script.sh
5. Observe that FOO=bar makes it to the java program but SPAM=eggs does not
   Now re-run the script again but this time add set -a to the script

   #!/bin/bash

   set -a

   SPAM=eggs

   java JavaEnvironmentVariables

6. Verify

   $ ./my_script.sh | grep SPAM

   SPAM=eggs