Shell Programming and Scripting

# ./justdoit hEu
'$1'= hEu

# ./justdoit H3y
'$1'= H3y

# ./justdoit H3E
'$1'=

## justdoit ##
 
#!/bin/bash
parameterone="$1"
if [[ "$parameterone" == "hEu" ]] || [[ "$parameterone" == "H3y" ]] ; then
            set -- "$parameterone" $1
else
            set -- "" $1
fi
echo "'\$1'= $1"

$(
 echo 'Enter Parameter: \c' >/dev/tty
 sed '
   /[^a-zA-Z0-9]/{
      s/.*/Must contain only letters and numbers: "&"/
      w /dev/tty
      d
     }
   q
  '
 )

$(
   l2=""
   while [ "$l2" = "" ]
   do
    echo 'Enter Parameter: \c' >/dev/tty
    line | read l
    echo "$l" | sed '/[^a-zA-Z0-9]/d' | read l2
    if [ "$l2" = "" ]
    then
     echo "Invalid, must be only numbers and letters and not empty: '$l'" | cat -vt >/dev/tty
    fi
   done

  echo "$l2"
 )

#!/bin/bash
parameterone="$1"
if [[ "$parameterone" == "hEu" ]] || [[ "$parameterone" == "H3y" ]] ; then
            caps=$(echo "$parameterone" | perl -pe 'y/a-z/A-Z/' )
            set -- "$caps" $1
else
            set -- "" $1
fi
echo "'\$1'= $1"