Bash scripting square brackets and ampersands

So I’m trying to create a startup script for Weblogic on Redhat.
There’s a few out there, but I wanted one that did everything I wanted and that I also understood.
I’m not an admin so this scripting thing is a dark art to me.

I’ll hopefully have the actual script in a later post but for now I noticed alot of the lines below in example init scripts I came across.

For the start function

[ ${RETVAL} -eq 0 ] && touch ${LOCKFILE}

For the stop function

[ ${RETVAL} -eq 0 ] && rm -f ${LOCKFILE}

So creation and removal of the lock file, problem for me was I didn’t quite understand what it was doing exactly, examples and tutorials kind of gloss over it as something to basic to explain, which is fair enough it is a basic built in function, I just didn’t know about it.

In bash [ is a built in command for test it doesn’t need the if
In bash && is a control operator, this says if the previous command is true (exit status 0) continue on

So the above line is a shortcut for

if [${RETVAL} -eq 0]; then  
   touch ${LOCKFILE}  
fi