Exporting Variables
Problem
You defined a variable in one script, but when you called another script it didn’t know about the variable.
Solution
Export variables that you want to pass on to other scripts:
export MYVAR export NAME=value
Discussion
Sometimes it’s a good thing that one script doesn’t know about the
other script’s variables. If you called a shell script from within a
for
loop in the first script, you
wouldn’t want the second script messing up the iterations of your
for
loop.
But sometimes you do want the information passed along. In those cases, you can export the variable so that its value is passed along to any other program that it invokes.
If you want to see a list of all the exported variables, just type
the built-in command env (or export -p
) for a list of each variable and its
value. All of these are available for your script when it runs. Many
have already been set up by the bash startup
scripts (see Chapter 16 for
more on configuring and customizing bash).
You can have the export statement just name the variable that will
be exported. Though the export statement can be put anywhere prior to
where you need the value to be exported, script writers often group
these export statements together like variable declarations at the front
of a script. You can also make the export
part of any variable assignment, though
that won’t work in old versions of the shell.
Once exported, you can assign repeatedly to the variable without exporting it each time. So, sometimes you’ll see ...
Get bash Cookbook now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.