Hour 13

1: Add tar file extraction to the mytar script.

Assume that the -x option indicates that the user wants to extract tar files and that the correct value of TARGS for extracting tar files is -xvf.

A1: One correct implementation is as follows: 
#!/bin/sh

USAGE="Usage: `basename $0` [-c|-t] [files|directories]"
if [ $# -lt 2 ] ; then
    echo "$USAGE" ;
    exit 1 ;
fi

case "$1" in
    -t|-x) TARGS=${1}vf ; shift
        for i in "$@" ; do
            if [ -f "$i" ] ; then
                FILES=`tar $TARGS "$i" 2>/dev/null`
                if [ $? -eq 0 ] ; then
                    echo ; echo "$i" ; echo "$FILES"
                else
                    echo "ERROR: $i not a tar file."
                fi
            else
                echo "ERROR: $i not a file."
            fi
        done
        ;;
    -c) shift ; TARGS="-cvf" ;
        tar $TARGS archive.tar "$@"
        ;;
     *) echo "$USAGE"
        exit 0
        ;;
esac
exit $?
2: Add the extract option to ...

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