Understanding a Linux Command Syntax that Fixed LibreOffice

Question

Greetings and pardon the lengthy title,

To preface: I solved an issue where after downloading LibreOffice, the splash screen would show up, but nothing would happen afterwards

Below is the solution that fixed my issue: Step 1. SAL_DISABLE_OPENCL=1 soffice Step 2. libre office should open - open Tools -> Options -> LibreOffice -> OpenCL and disable the option "Allow use of OpenCL"

That being said, I'm trying to understand what happened in step 1. It appears to me that we are opening a subshell via the soffice command with the variable SAL_DISABLE_OPENCL changed in the context of said subshell

I've never seen or read about this before, and gave up trying to google the correct string of words. Does this concept have a name? I tried soffice --help but there is nothing to indicate this syntax

Any help is greatly appreciated, thanks!

Answer 1

Running SAL_DISABLE_OPENCL=1 soffice runs the program soffice passing to it the environment variable SAL_DISABLE_OPENCL set to the value 1. It does not run a subshell, it is run on your current shell. This syntax is described in the bash manual:

The environment for any simple command or function may be augmented temporarily by prefixing it with parameter assignments, as described in Shell Parameters. These assignment statements affect only the environment seen by that command.

That environment variable is a value treated specially by LibreOffice to force that option to be disabled.