a better manpage interface

gistfile1.txt

m() {
        dpkg -s dialog &>/dev/null || { echo "Needs 'dialog' package which is not installed on this system!" && return; }
        [[ $# -lt 1 ]] && echo 'Man page name consisting of a single word expected but not given.' && return
        MANPAGE=$1
        [[ -n $2 ]] && DEFAULTCHOICE=$2 || DEFAULTCHOICE='0'
        man $MANPAGE > /dev/null 2>&1 || { echo $MANPAGE man page not present on this system!; return; }
        mapfile -t OUTLINE < <(PAGER=cat man $MANPAGE | grep ^\\w | grep -v -e AUTHORS -e COPYRIGHT | sed '1d;$d')
        RESULTSIZE=$(echo ${#OUTLINE[*]})
        CHOICE=$(
                dialog --keep-tite --default-item "$DEFAULTCHOICE" --menu "$(
                        echo -n $MANPAGE | tr '[a-z]' '[A-Z]'
                ) manpage contents" $(( $RESULTSIZE + 8 )) 35 $RESULTSIZE $(
                        COUNT=0
                        for i in $( seq 0 $(( ${#OUTLINE[@]} - 1 )) )
                        do
                                echo -n $COUNT
                                echo -n " $( echo "${OUTLINE[i]}" | sed 's/ /\_/g' ) " 
                                (( COUNT++ ))
                        done
                ) 2>&1 >/dev/tty || echo CANCEL
        )
        [[ $CHOICE =~ "CANCEL" ]] && return
        MANPAGER="less +/^$( echo ${OUTLINE[$CHOICE]} | sed 's/ /\\ /g' )" man $MANPAGE
        m $MANPAGE $CHOICE
}