I understand that a .gitignore file cloaks specified files from Git's version control.

How do I tell .gitignore to ignore everything except the files I'm tracking with Git? Something like:

# Ignore everything:
*
Do not ignore these files:
script.pl
template.latex

An optional prefix ! which negates the pattern; any matching file excluded by a previous pattern will become included again. If a negated pattern matches, this will override lower precedence patterns sources.

# Ignore everything
*
But not these files…
!.gitignore
!script.pl
!template.latex
etc…
…even if they are in subdirectories
!*/
if the files to be tracked are in subdirectories
!/a/b/file1.txt
!/a/b/c/*