Script for automating regression testing

I am writing a simple script to automate my regression testing. I am new to bash scripting and my goal is achieve the most efficient and clean code. I have written a simple function to allow me to select which subject I would like to test. This will loop until I select the exit option. Again, this is quite simple; however I am looking for some feedback on how I can improve.

BIO=biology

showMenu () {
    echo "What subject would like to regression test?"
    echo "1) Physics"
    echo "2) Sociology"
    echo "3) Biology"
    echo "4) Quit"
}

while [ 0 ]
do
    showMenu
    read CHOICE
    case "$CHOICE" in

    "1")
        read SUBJECT
        SUBJECT=physics
        echo "LOG: REGRESSION TESTING $SUBJECT" $SUBJECT
        GENERATE_CSS=`lessc /home/developer/oer.exports/css/ccap-$BIO.less > /home/developer/oer.exports/css/ccap-$BIO.css`
        echo "LOG: CSS GENERATION COMPLETE"
        GENERATE_PDF=`python collectiondbk2pdf.py -v -s ccap-$BIO -d ./test-ccap/col$SUBJECT $SUBJECT.pdf -t tempdir/$SUBJECT`
        echo "LOG: GENERATING $SUBJECT PDF WITH $BIO CSS STYLE"
        ;;
    "2")
            read SUBJECT
        SUBJECT=sociology
        echo "LOG: REGRESSION TESTING SOCIOLOGY" $SUBJECT
        GENERATE_CSS=`lessc /home/developer/oer.exports/css/ccap-$BIO.less > /home/developer/oer.exports/css/ccap-$BIO.css`
        echo "LOG: CSS GENERATION COMPLETE"
        GENERATE_PDF=`python collectiondbk2pdf.py -v -s ccap-$BIO -d ./test-ccap/col$SUBJECT $SUBJECT.pdf -t tempdir/$SUBJECT`
        echo "LOG: GENERATING $SUBJECT PDF WITH $BIO CSS STYLE"
        ;;
    "3")
        echo "Biology"
        DIFF=`diffpdf -a --debug=2 /tmp/pdf/diff bio.pdf bio_slicer.pdf`
        echo "LOG: DIFF DEV vs STAGING NOW AVAILABLE FOR PDF VIEW. "
        ;;      
    "4")
        echo "Exiting now..."
        exit
        ;;

    esac
done

• while : is a standard idiom for "loop forever" in bash. The colon (:) is a synonym for true.

• Prefer $(command) to `command ("backticks"). The former allows you to nest; the latter does not.

• Though in your case, you don't need the backticks at all. These are for capturing the output of the command, which you don't use anywhere.

• It isn't clear why you have the read SUBJECT inside each case -- you throw away the value in the very next statement.






• Don't do this: lessc ccap-$BIO.less > ccap-$BIO.css. (It's a classic mistake in shell scripting; everyone's been bit by it.) This will nuke the file -- it will be truncated by the shell, overwriting the contents before lessc has the chance to read it.




Aside from your code: if your goal is to regenerate the output files whenever one of the input files has changed, you should consider learning make`. With a 10-20 line makefile, you can automatically regenerate whichever of the output files need updating whenever one of the input files change.

StackExchange Code Review Q#17656, answer score: 2