A message for Linux.com registered users: We are in the process of making changes to the Linux forums. Starting Monday, 8/13/18 at 6:00 PM PT, you will be unable to access the forums. They will re-launch as soon as possible on Wednesday, 8/15/18 with new features and improved functionality. Thank you for your patience and stay tuned for the new improved forums.
Deciphering lines of code
Hey everyone I don't know if this is the right place to ask this question but I am trying to learn what different lines of code do and I need some help. I am looking at the Save command specifically. It was written to save files and back then up to a directory for later backup usage. The problem that I am having is in the first part of the code. For instance on this line
if [! -d $1];then echo $1 is not a directory; exit 1; fi
I know the fi means that the line is finished and the echo is a command to run the $1 file but what is the first part? Any help will be appreciated. Thanks