Examine memory with ASCII view in GDB

gdb_ascii_examine.txt

define xac
    dont-repeat
    set $addr = (char *)($arg0)
    set $endaddr = $addr + $arg1
    while $addr < $endaddr
        printf "%p: ", $addr
        set $lineendaddr = $addr + 8
        if $lineendaddr > $endaddr
            set $lineendaddr = $endaddr
        end
        set $a = $addr
        while $a < $lineendaddr
            printf "%#02x ", *(char *)$a
            set $a++
        end
        printf "'"
        set $a = $addr
        while $a < $lineendaddr
            printf "%c", *(char *)$a
            set $a++
        end
        printf "'\n"
        set $addr = $addr + 8
    end
end

document xac
usage: xac address count
end

Taken from http://stackoverflow.com/a/25813099/588966