export in scripts

[Mrg_2]

Why do people use export with variables in scripts? I can only assume it is to set the environment variables. Are the exports temporary just until the process stops running? I am trying to gain a better understanding on the use of export in scripts.
Examples are below.

export ORACLE_HOME=/oracle/app/product/forms9i
export TWO_TASK=ID
export TERM=vt100

[James R. Ferguson · Accepted solution]

Hi:

Yes, one 'export's a variable from a script to propagate it into any child environment.

Yes, the environment exists only for the lifetime of the process and any child processes that inherit the environmental content.

One way to pass variables from one script to another is to "source" or read a file:

# cat /tmp/A
#!/usr/bin/sh
fruit=apple

# cat /tmp/B
#!/usr/bin/sh
. /tmp/A
echo "I want a(n) ${fruit}"

# /tmp/B
I want a(n) apple

...Note the dot character; followed by whitespace; followed by the script to be "sourced" (read). In this case, the variables declared in "A" are only available to "B" for its use.

Regards!

...JRF...

[Wouter Jagers]

Exporting a variable makes it available to child processes.

Easily demonstrated in a shell:

babylon-4:itrc wout$ echo $TEST
value
babylon-4:itrc wout$ sh
sh-3.2$ echo $TEST

sh-3.2$ exit
exit
babylon-4:itrc wout$ export TEST
babylon-4:itrc wout$ sh
sh-3.2$ echo $TEST
value

Cheers
Wout

[Mrg_2]

Thanks for the quick replies very helpful.