You don't necessarily need a script to do that. You can
, but I would guess most people would suggest setting up an alias instead. I'll give you equivalents for both (alias and script).
For an alias, you have two choices on where to put it: /etc/bashrc or ~/.bashrc
Making a change to /etc/bashrc will make the alias available to every user on the system. Making the change to ~/.bashrc will make the alias available only for that particular user. Define an alias like this:
alias mzip='iw -m /dev/sda -mp /zip'
After finishing, source the file you changed. Either source /etc/bahrc
or source ~/.bashrc
You only have to source the file for any shells you currently have open. The next time you log in, the alias will be ready automatically.
Now, for the shell script...
Open a text editor and type in this (or copy-paste):
iw -m /dev/sda -mp /zip
Save the file as mzip (the name you want to use for the command). Then execute the following command:
chmod a+x mzip
That command makes the script executable. Now, if you want to type "mzip" on the command line no matter where you are, then move the mzip file to a spot somewhere in your PATH variable. A good place would probably be /usr/local/bin
And that's all there is to it.