Shell Programming and Scripting

My professor has given me a couple of functions that I am to use to accomplish the task of replacing spaces in file and/or directory names with hyphens.

(i.e. A B/C D/E F and you want to rename that to A B/C D/E-F would be an example of changing the file and leaving the directories)

These are two of the functions I am to use:

Code:

pathname ()
    {
    # function provided for the student
    print -- "${1%/*}"
    }

basename ()
    {
    # function provided for the student
    print -- "${1##*/}"
    }

Basically they are to be used thusly:

1. FILE="A B/C D/E F"
2. BASENAME=`basename "$FILE"`
3. PATHNAME=`pathname "$FILE"`
4. NEWNAME=`echo $BASENAME | some sed command to change spaces to -'s '` # I will leave the sed command to you :-)
5. Now you have the pieces to do the rename à $FILE gets moved to "$PATHNAME/$NEWNAME"

I am wondering if someone can break down, in detail, what those two functions actually do. I'm not sure I understand how the regex and print fucntion work in them, and why are there two hyphens after print. Thanks in advance. Sorry for the long post.

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