Proper way to setup environment variables

shogun1234 · 11-05-2019, 06:04 PM

In command line, I understand I can export environment variable by export. For instance,

Code:

$ export JAVA_OPTS="..."
$ java -cp ./ $JAVA_OPTS ...

But sometimes I seems to see some usage such

Code:

env JAVA_OPTS="..."; java -cp ... $JAVA_OPTS

or

Code:

JAVA_OPTS="..."; java -cp ... $JAVA_OPTS

I can't remember the exact way those commands to export environment variables (so I believe the syntax I use could be wrong). Thus I am interested to learn what's a more appropriate way to export environment variables or (if it's just different syntax as unix allows different approach the goal by different ways) the differences between those syntax.

Thanks

scasey · 11-05-2019, 08:20 PM

There's lots of information available on-line.
I believe that all three of your examples are "proper," each in their place. The main difference is where the variables live and whether or not they get propagated.

export is a bash built-in: see man export, then search for export. Other shells may have different syntax for exporting a variable.
see man env

What, specifically, are you concerned about?