nmap(1) -n -p80 -sS -PN --open | grep.1 "Nmap scan report" | awk.1posix '{print $5}' | while read(1posix) IP; do ping(8) -c 1 $IP && plan9-echo.1 "I can ping $IP" ; done
Network exploration tool and security / port scanner
-n (No DNS resolution) .
    Tells Nmap to never do reverse DNS resolution on the active IP addresses it finds. Since DNS can be
    slow even with Nmap´s built-in parallel stub resolver, this option can slash scanning times.
-p port ranges (Only scan specified ports) .
    This option specifies which ports you want to scan and overrides the default. Individual port numbers
    are OK, as are ranges separated by a hyphen (e.g.  1-1023). The beginning and/or end values of a
    range may be omitted, causing Nmap to use 1 and 65535, respectively. So you can specify -p- to scan
    ports from 1 through 65535. Scanning port zero.  is allowed if you specify it explicitly. For IP
    protocol scanning (-sO), this option specifies the protocol numbers you wish to scan for (0–255).

    When scanning both TCP and UDP ports, you can specify a particular protocol by preceding the port
    numbers by T: or U:. The qualifier lasts until you specify another qualifier. For example, the
    argument -p U:53,111,137,T:21-25,80,139,8080 would scan UDP ports 53, 111,and 137, as well as the
    listed TCP ports. Note that to scan both UDP and TCP, you have to specify -sU and at least one TCP
    scan type (such as -sS, -sF, or -sT). If no protocol qualifier is given, the port numbers are added
    to all protocol lists.  Ports can also be specified by name according to what the port is referred to
    in the nmap-services. You can even use the wildcards * and ? with the names. For example, to scan FTP
    and all ports whose names begin with “http”, use -p ftp,http*. Be careful about shell expansions and
    quote the argument to -p if unsure.

    Ranges of ports can be surrounded by square brackets to indicate ports inside that range that appear
    in nmap-services. For example, the following will scan all ports in nmap-services equal to or below
    1024: -p [-1024]. Be careful with shell expansions and quote the argument to -p if unsure.
-sS (TCP SYN scan) .
    SYN scan is the default and most popular scan option for good reasons. It can be performed quickly,
    scanning thousands of ports per second on a fast network not hampered by restrictive firewalls. SYN
    scan is relatively unobtrusive and stealthy, since it never completes TCP connections. It also works
    against any compliant TCP stack rather than depending on idiosyncrasies of specific platforms as
    Nmap´s FIN/NULL/Xmas, Maimon and idle scans do. It also allows clear, reliable differentiation
    between the open, closed, and filtered states.

    This technique is often referred to as half-open scanning, because you don´t open a full TCP
    connection. You send a SYN packet, as if you are going to open a real connection and then wait for a
    response. A SYN/ACK indicates the port is listening (open), while a RST (reset) is indicative of a
    non-listener. If no response is received after several retransmissions, the port is marked as
    filtered. The port is also marked filtered if an ICMP unreachable error (type 3, code 1, 2, 3, 9, 10,
    or 13) is received.
-PN (No ping) .
    This option skips the Nmap discovery stage altogether. Normally, Nmap uses this stage to determine
    active machines for heavier scanning. By default, Nmap only performs heavy probing such as port
    scans, version detection, or OS detection against hosts that are found to be up. Disabling host
    discovery with -PN causes Nmap to attempt the requested scanning functions against every target IP
    address specified. So if a class B sized target address space (/16) is specified on the command line,
    all 65,536 IP addresses are scanned. Proper host discovery is skipped as with the list scan, but
    instead of stopping and printing the target list, Nmap continues to perform requested functions as if
    each target IP is active. To skip ping scan and port scan, while still allowing NSE to run, use the
    two options -PN -sP together.

    For machines on a local ethernet network, ARP scanning will still be performed (unless --send-ip is
    specified) because Nmap needs MAC addresses to further scan target hosts. This option flag used to be
    P0 (uses zero), but was renamed to avoid confusion with protocol ping´s PO (uses the letter O) flag.
--open (Show only open (or possibly open) ports) .
    Sometimes you only care about ports you can actually connect to (open ones), and don´t want results
    cluttered with closed, filtered, and closed|filtered ports. Output customization is normally done
    after the scan using tools such as grep, awk, and Perl, but this feature was added due to
    overwhelming requests. Specify --open to only see open, open|filtered, and unfiltered ports. These
    three ports are treated just as they normally are, which means that open|filtered and unfiltered may
    be condensed into counts if there are an overwhelming number of them.
nmap [Scan Type...] [Options] {target specification}
    A  pipeline is a sequence of one or more commands separated by one of the control operators | or |&.  The
    format for a pipeline is:

           [time [-p]] [ ! ] command [ [||&] command2 ... ]

    The standard output of command is connected  via  a  pipe  to  the  standard  input  of  command2.   This
    connection  is performed before any redirections specified by the command (see REDIRECTION below).  If |&
    is used, the standard error of command is connected to command2's standard input through the pipe; it  is
    shorthand  for  2>&1  |.   This  implicit  redirection  of  the  standard  error  is  performed after any
    redirections specified by the command.

    The return status of a pipeline is the exit status of the last command, unless  the  pipefail  option  is
    enabled.   If  pipefail  is  enabled,  the  pipeline's return status is the value of the last (rightmost)
    command to exit with a non-zero status, or zero if all commands exit successfully.  If the reserved  word
    !   precedes  a  pipeline, the exit status of that pipeline is the logical negation of the exit status as
    described above.  The shell waits for all commands in the pipeline to terminate before returning a value.

    If the time reserved word precedes a pipeline, the elapsed as well as user and system  time  consumed  by
    its execution are reported when the pipeline terminates.  The -p option changes the output format to that
    specified by POSIX.  When the shell is in posix mode, it does not recognize time as a  reserved  word  if
    the  next  token begins with a `-'.  The TIMEFORMAT variable may be set to a format string that specifies
    how the timing information should be displayed; see the description of TIMEFORMAT under  Shell  Variables

    When the shell is in posix mode, time may be followed by a newline.  In this case, the shell displays the
    total user and system time consumed by the shell and its children.  The TIMEFORMAT variable may  be  used
    to specify the format of the time information.

    Each command in a pipeline is executed as a separate process (i.e., in a subshell).
print lines matching a pattern
grep searches the named input FILEs (or standard input if no files are named, or if a single hyphen-minus
(-) is given as file name) for lines containing a match to the given PATTERN.  By  default,  grep  prints
the matching lines.
pattern scanning and processing language
       If no -f option is specified, the first operand to awk shall be the text of the awk  program.  The
       application shall supply the program operand as a single argument to awk. If the text does not end
       in a <newline>, awk shall interpret the text as if it did.

       Either of the following two types of argument can be intermixed:

       A pathname of a file that contains the input to be read, which  is  matched  against  the  set  of
       patterns  in  the  program.  If  no file operands are specified, or if a file operand is '-' , the
       standard input shall be used.

       An operand that begins with an underscore or alphabetic character from the portable character  set
       (see  the  table  in  the  Base  Definitions volume of IEEE Std 1003.1-2001, Section 6.1, Portable
       Character Set), followed by a sequence of underscores, digits, and alphabetics from  the  portable
       character  set,  followed  by the '=' character, shall specify a variable assignment rather than a
       pathname. The characters before the '=' represent the name of an awk variable; if that name is  an
       awk  reserved  word  (see  Grammar ) the behavior is undefined. The characters following the equal
       sign shall be interpreted as if they appeared in the  awk  program  preceded  and  followed  by  a
       double-quote ( ' )' character, as a STRING token (see Grammar ), except that if the last character
       is an unescaped backslash, it shall be interpreted as a literal backslash rather than as the first
       character  of  the  sequence  "\"" . The variable shall be assigned the value of that STRING token
       and, if appropriate, shall be considered a numeric string (see Expressions in awk ), the  variable
       shall  also be assigned its numeric value. Each such variable assignment shall occur just prior to
       the processing of the following file, if any. Thus, an assignment before the first  file  argument
       shall  be  executed  after  the  BEGIN  actions  (if any), while an assignment after the last file
       argument shall occur before the END actions (if any). If there are no file arguments,  assignments
       shall be executed before processing the standard input.
while list-1; do list-2; done
until list-1; do list-2; done
       The while command continuously executes the list list-2 as long as the last command  in  the  list
       list-1  returns  an  exit  status  of  zero.  The until command is identical to the while command,
       except that the test is negated; list-2 is executed as long as the last command in list-1  returns
       a non-zero exit status.  The exit status of the while and until commands is the exit status of the
       last command executed in list-2, or zero if none was executed.
read a line from standard input
send ICMP ECHO_REQUEST packets to network hosts
-c count
        Stop after sending (and receiving) count ECHO_RESPONSE packets.
ping [-Rdfnqrv] [-c count] [-i wait] [-l preload] [-p pattern] [-s packetsize] host
AND and OR lists are sequences of one of more pipelines separated by the &&  and  ||  control  operators,
respectively.  AND and OR lists are executed with left associativity.  An AND list has the form

       command1 && command2

command2 is executed if, and only if, command1 returns an exit status of zero.

An OR list has the form

       command1 || command2

command2  is  executed  if and only if command1 returns a non-zero exit status.  The return status of AND
and OR lists is the exit status of the last command executed in the list.
print arguments
source manpages: nmapgrepawkreadpingplan9-echo