gen v1.6.5 - now fully POSIX compliant

#!/bin/sh

# gen v1.6.5 - Generates random patterns of characters with the option to exclude certain regions of the ASCII table.

. whrandom.sh

IFS=$IFS","
WH_LOOP=1000
WH_ALGO=WH_OLD
WH_MAX=126
WH_DEL=" "
NOGO="0-32,34,39"
RC=0
RND=33

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.sh -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)
    -f ......................... no linefeed at the end of the string
    -d [string] .... put [string] between each character as delimiter
    -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
}

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

while getopts :c:C:d:D:e:E:i:I:lLuUnNsSfFmM OPT; do
    case $OPT in
    c|C)
        [ -z "${OPTARG##*[!0-9]*}" ] && ERROR "C needs a number, nothing else!"
        LOOP=$OPTARG
        ;;
    d|D)
        DEL="$OPTARG"
        ;;
    e|E)
        expr "$OPTARG" : '^[0-9]\{1,\}-[0-9]\{1,\}$' > /dev/null || ERROR "No valid ASCII code region."
        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)
        [ $((L=$L+1)) -eq 1 ] && SKIP_LIST=$SKIP_LIST"97-122,"
        ;;
    u|U)
        [ $((U=$U+1)) -eq 1 ] && SKIP_LIST=$SKIP_LIST"65-90,"
        ;;
    n|N)
        [ $((N=$N+1)) -eq 1 ] && SKIP_LIST=$SKIP_LIST"48-57,"
        ;;
    s|S)
        [ $((S=$S+1)) -eq 1 ] && SKIP_LIST=$SKIP_LIST"33-47,58-64,91-96,123-126,"
        ;;
    f|F)
        LFEED=1
        ;;
    m|M)
        M=1
        ;;
    :)
        ERROR "$OPTARG requires an argument"
        ;;
    \?)
        ERROR "Unknown option: $OPTARG"
        ;;
    esac
done

[ -z $LOOP ] && ERROR "Number of characters MUST be given!"

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

while [ $LOOP -gt 0 ]; do
    ARRAY=$(WH_RANDOM)
    for RND in $ARRAY; do
        if STRIP; then
            [ $LOOP -eq 1 ] && DEL=
            CHAR=$(printf "\\$(printf '%03o' "$RND")")"$DEL"
            printf "%s" "$CHAR"
            CB=$CB$CHAR
            [ $((LOOP=$LOOP-1)) -eq 0 ] && break
        fi
    done
done
if [ -n "$M" ]; then
    if command -v xclip 1>/dev/null; then
        printf "$CB" | xclip -i -selection clipboard
        printf "\nString was copied to clipboard."
    else
        printf "\n\033[0;31mUnable to copy string to clipboard - xclip not found.\033[0m"
    fi
fi
[ -z $LFEED ] && echo