SHELL

gitignore ignore everything except

# ignore everything in current directory
/*

# !pattern now negates the "ignore everything" and keeps 'pattern'

# keep .gitignore
!.gitignore 

# keep mydirectory, along with everything inside it 
!mydirectory/

.gitignore everything except

# 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/*