check if port is a num and if it's privated (<1025), returns 0 on success, 1 otherwise (bashfunction)

isprivport.bash

# check if port is a num and if it's privated (<1025), returns 0 on success, 1 otherwise
# @param int portnumber

function isprivport()
{   
    [ -z "$1" ] && return 1

    printf "%s\\n" "$1" | grep -v "[^0-9]" >/dev/null
    if [ $? -eq 0 ]; then
        [ $1 -gt 0 ] && [ $1 -lt 1025 ] && return 0 || return 1
    else
        return 1
    fi
}