Shell Programming and Scripting

Ok, I'm trying to learn Unix shell scripting. At work, I'm an administrator of a system. Part of my job, I work in Unix. I can get things to work, but I'm not the most efficient at Unix CLI.

I'm trying to figure out how to write a bash script. Right now I have a very crude and unprofessional script, but it works. I'd like to re-write it to be a little more professional.

What the script does is looks in 4 different folders and checks for any files that have files that look like filename.noload. I then right now, rename all the files to filename.1.log. There is also a .meta file that I rename so it's .1.meta. I do the .1.log part to signify the files have been tried once already.

So far, every instance of these files, when I try them a second time, they've processed everytime. But I was discussing with a co-worker and he doesn't think I should have it hard coded but actually increment the number in the file in case it does have to go more than one retry.

But right now, I have a script that changes directory to each of the directories and then runs the rename command to rename all the files from .noload to .1.log and the same for .meta.

I'm trying to understand functions. I need some basic explanation on how I could use a function for this. I keep trying to visualize how I can take 4 different variables that I could store the 4 paths to the .noloads files. Then I'm thinking it should be able to call the same function multiple times to run the same code to first check (using an if statement), if there are .noload files there. If not, exit the function and go to the next one. I need more understanding of functions...

Then also, I have a script that checks the Done folder for files that were processed the second time (so they have a .1.log in the name) and then alerts me that it happened. It would be nice to incorporate this into this script.

Show us your current working scripts.