U simply takes the command line which follows it and writes it to a command file called sys:u.cmd, so that it can be easily recalled later just by typing U. For example:

.U dir/udate/cdate/adate *.bas[],*.run[*,0]

After executing the above command, you would then be able to enter just u then Enter to execute the command:

dir/udate/cdate/adate *.bas[],*.run[*,0]

Since recording one command is of limited value (given that you can use ^r to retrieve previously typed commands from the command history buffer), you can make unlimited copies of the U.LIT command under different names, which will work the same way but which will record their command lines in the correspondingly named command files.

Example

.COPY U2=SYS:U.LIT

.U2 DIR/UDATE/CDATE/ADATE

The above would create a command file called U2 which could be later executed to execute the DIR/UDATE/CDATE/ADATE command line.