PING(8) UNIX System Manager's Manual PING(8)
NAME
ping - send ICMP ECHO_REQUEST packets to network hosts
SYNOPSIS
ping [-dfnqrvR] [-c count] [-i wait] [-l preload] [-p pattern] [-s
packetsize]
DESCRIPTION
Ping uses the ICMP protocol's mandatory ECHO_REQUEST datagram to elicit
an ICMP ECHO_RESPONSE from a host or gateway. ECHO_REQUEST datagrams
(``pings'') have an IP and ICMP header, followed by a ``struct timeval''
and then an arbitrary number of ``pad'' bytes used to fill out the pack-
et. The options are as follows: Other options are:
-c count
Stop after sending (and receiving) count ECHO_RESPONSE packets.
-d Set the SO_DEBUG option on the socket being used.
-f Flood ping. Outputs packets as fast as they come back or one
hundred times per second, whichever is more. For every
ECHO_REQUEST sent a period ``.'' is printed, while for ever
ECHO_REPLY received a backspace is printed. This provides a
rapid display of how many packets are being dropped. Only the
super-user may use this option. This can be very hard on a net-
work and should be used with caution.
-i wait
Wait wait seconds between sending each packet. The default is to
wait for one second between each packet. This option is incom-
patible with the -f option.
-l preload
If preload is specified, ping sends that many packets as fast as
possible before falling into its normal mode of behavior. Only
the super-user may use this option.
-n Numeric output only. No attempt will be made to lookup symbolic
names for host addresses.
-p pattern
You may specify up to 16 ``pad'' bytes to fill out the packet you
send. This is useful for diagnosing data-dependent problems in a
network. For example, ``-p ff'' will cause the sent packet to be
filled with all ones.
-q Quiet output. Nothing is displayed except the summary lines at
startup time and when finished.
-R Record route. Includes the RECORD_ROUTE option in the
ECHO_REQUEST packet and displays the route buffer on returned
packets. Note that the IP header is only large enough for nine
such routes. Many hosts ignore or discard this option.
-r Bypass the normal routing tables and send directly to a host on
an attached network. If the host is not on a directly-attached
network, an error is returned. This option can be used to ping a
local host through an interface that has no route through it
(e.g., after the interface was dropped by routed(8)).
-s packetsize
Specifies the number of data bytes to be sent. The default is
56, which translates into 64 ICMP data bytes when combined with
the 8 bytes of ICMP header data.
-v Verbose output. ICMP packets other than ECHO_RESPONSE that are
received are listed.
When using ping for fault isolation, it should first be run on the local
host, to verify that the local network interface is up and running.
Then, hosts and gateways further and further away should be ``pinged''.
Round-trip times and packet loss statistics are computed. If duplicate
packets are received, they are not included in the packet loss calcula-
tion, although the round trip time of these packets is used in calculat-
ing the minimum/average/maximum round-trip time numbers. When the speci-
fied number of packets have been sent (and received) or if the program is
terminated with a SIGINT, a brief summary is displayed.
If ping does not receive any reply packets at all it will exit with code
1. On error it exits with code 2. Otherwise it exits with code 0. This
makes it possible to use the exit code to see if a host is alive or not.
This program is intended for use in network testing, measurement and man-
agement. Because of the load it can impose on the network, it is unwise
to use ping during normal operations or from automated scripts.