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For the rest of this section, I show how variables and commands may appear in a shell script. To try out any of those examples, however, you can simply type them into a shell, as shown in the previous example.

In the following example, MYFILENAME is set to /home/digby/myfile.txt. Next, the FILE variable is set to myfile.txt and DIR is set to /home/digby. In the NAME variable, the filename is cut down simply to myfile; then, in the EXTENSION variable, the file extension is set to txt. (To try these out, you can type them at a shell prompt as in the previous example and echo the value of each variable to see how it is set.) Type the code on the left. The material on the right side describes the action.

 MYFILENAME=/home/digby/myfile.txt: Sets the value of MYFILENAME

 FILE=${MYFILENAME##*/}: FILE becomes myfile.txt

 DIR=${MYFILENAME%/*}: DIR becomes /home/digby

 NAME=${FILE%.*}: NAME becomes myfile

 EXTENSION=${FILE##*.}: EXTENSION becomes txt