If you’re fed up with typing in your commands each time you want to build a new version of CM7, take a look at the bash script that XDA forum member Jazi has put together.
The script edits and updates the build.prop i the zip with the time and your name (you’ll need to replace Jazi with your own). Note that the output directory must be empty for the build to run properly. If this isn’t the case, you’ll need to remove the first two lines of the code.
Some of you may know that a 64 bit system is required to compile CM7 since compiling Android 2.3 from source requires 64 bit. However, it is possible to build 2.3 upwards if a few tweaks are made to the make file and XDA forum member wes342 has helpfully posted his own make script that will do everything on a 32 bit system.