gen 1.5.4 (fixed bug in exclude option; more clean up)

#!/bin/bash

# gen v1.5.4 - Generates random patterns of characters with the option to exclude certain regions of the ASCII table.

NOGO="0-32,34,39"
SKIP_LIST=
KEEP_LIST=
RC=0
CB=
M=0
typeset -i RND=33
typeset -i CHK
typeset -i START_N
typeset -i END_N

function ERROR() # display error message, infotext and exit with return code 1
{
    printf "\n\033[0;31mError - $1\033[0;32m\n\n"
    cat <<EOF
 Usage: gen.bash -c [number of characters] -luns -e [start-end] -i [character(s)] -m

    -c [n] .............. number of random characters to be generated
    -l ................................... exclude lower case letters
    -u ................................... exclude upper case letters
    -n .............................................. exclude numbers
    -s ........................................ exclude special signs
    -e [start-end] .............. exclude a custom ASCII table region
    -i [character(s)] .................. include certain character(s)
    -m .......................... memorize (copy string to clipboard)

 If using the -e option, you may enter a single ASCII code or a whole range from start to end code with a minus "-"
 in between. You can also enter several codes and ranges, all separated by comma (i.e. -e 33,58-64,... and so on).
 The -i option will add characters on top of of the excluded ones meaning that they will be added even if they belong
 to an excluded group. Using this option you may enter a single character or a whole group in a single row.
 If you try to include special signs you may put them in quotes (single ' or double " while single quotes are more secure)
 to prevent the shell from misinterpreting them as function (i.e. -i '&/\' ). Thus single and double quotes can't be
 used as part of the random pattern at all. Remember that xclip must be installed in order to use the -m option.
EOF
    printf "\033[0m\n"
    exit 1
}

function STRIP() # strip random number down to a printable ASCII code & check if it's supposed to be kept
{
    while [ $RND -gt 126 ]; do RND=$RND/10; done
    IFS=","
    for RANGE in $NOGO; do
        START_N=${RANGE%-*}
        END_N=${RANGE#*-}
        if [ $RND -ge $START_N ] && [ $RND -le $END_N ]; then return 1; fi
    done
    for RANGE in $SKIP_LIST; do
        START_N=${RANGE%-*}
        END_N=${RANGE#*-}
        if [ $RND -ge $START_N ] && [ $RND -le $END_N ]; then
            RC=1
            if [ -n "$KEEP_LIST" ]; then
                for KEEP_NR in $KEEP_LIST; do
                    if [ $RND -eq $KEEP_NR ]; then RC=0; fi
                done
            fi
            return $RC
        fi
    done
}

while getopts :c:C:e:E:i:I:lLuUnNsSmM OPT; do
    case $OPT in
    c|C)
        if [[ ! $OPTARG =~ ^[0-9]+$ ]]; then ERROR "C needs a number, nothing else!"; fi
        typeset -i LOOP=$OPTARG
        ;;
    e|E)
        if [[ ! $OPTARG =~ ^[0-9]+-?[0-9]+$ ]]; then ERROR "No valid ASCII code region."; fi
        SKIP_LIST=$SKIP_LIST","$OPTARG
        ;;
    i|I)
        KEEP_LIST=$(for CHR in $(echo $OPTARG | sed -e 's/\(.\)/\1\n/g'); do printf '%d' "'$CHR"; printf ","; done)
        ;;
    l|L)
        if [ -z $L ]; then
            SKIP_LIST=$SKIP_LIST"97-122,"
            L=1
        fi
        ;;
    u|U)
        if [ -z $U ]; then
            SKIP_LIST=$SKIP_LIST"65-90,"
            U=1
        fi
        ;;
    n|N)
        if [ -z $N ]; then
            SKIP_LIST=$SKIP_LIST"48-57,"
            N=1
        fi
        ;;
    s|S)
        if [ -z $S ]; then
            SKIP_LIST=$SKIP_LIST"33-47,58-64,91-96,123-126,"
            S=1
        fi
        ;;
    m|M)
        M=1
        ;;
    :)
        ERROR "$OPTARG requires an argument"
        ;;
    \?)
        ERROR "Unknown option: $OPTARG"
        ;;
    esac
done

if [ -z $LOOP ]; then ERROR "Number of characters MUST be given!"; fi

while [ $RND -le 126 ]; do
    if STRIP; then CHK=$CHK+1; fi
    RND=$RND+1
done
if [ -z $CHK ]; then ERROR "Good job. You've just excluded the whole ASCII table. Try again!"; fi

while [ $LOOP -gt 0 ]; do
    RND=$RANDOM
    if STRIP; then
        CHAR=$(printf "\\$(printf '%03o' "$RND")")
        echo -n "$CHAR"
        CB=$CB$CHAR
        LOOP=$LOOP-1
    fi
done
if [ $M -eq 1 ]; then
    if command -v xclip 1>/dev/null; then
        echo -n "$CB" | xclip -i -selection clipboard
    else
        printf "\n\033[0;31mUnable to copy string to clipboard - xclip not found.\033[0m"
    fi
fi
echo