topic Re: export in scripts in Operating System - HP-UX

export in scripts

Mrg_2 — Tue, 13 Oct 2009 15:42:55 GMT

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

Re: export in scripts

James R. Ferguson — Tue, 13 Oct 2009 15:50:24 GMT

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...

Re: export in scripts

Wouter Jagers — Tue, 13 Oct 2009 15:53:29 GMT

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

Re: export in scripts

Mrg_2 — Tue, 13 Oct 2009 16:20:27 GMT

Thanks for the quick replies very helpful.