Linux Command Directory


Linux in a Nutshell

This directory of Linux commands is from Linux in a Nutshell, 5th Edition.

Click on any of the 687 commands below to get a description and list of available options. All links in the command summaries point to the online version of the book on Safari Bookshelf.

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traceroute

traceroute [options] host [packetsize]

TCP/IP command. Trace route taken by packets to reach network host. traceroute attempts tracing by launching UDP probe packets with a small TTL (time-to-live), then listening for an ICMP "time exceeded" reply from a gateway. host is the destination hostname or the IP number of the host to reach. packetsize is the packet size in bytes of the probe datagram. Default is 40 bytes.

Options

-d

Turn on socket-level debugging.

-f n

Set the initial time-to-live to n hops.

-F

Set the "don't fragment" bit.

-g addr

Enable the IP LSRR (Loose Source Record Route) option in addition to the TTL tests, to ask how someone at IP address addr can reach a particular target.

-i interface

Specify the network interface for getting the source IP address for outgoing probe packets. Useful with a multi-homed host. Also see the -s option.

-I

Use ICMP ECHO requests instead of UDP datagrams.

-m max_ttl

Set maximum time-to-live used in outgoing probe packets to max-ttl hops. Default is 30.

-n

Show numerical addresses; do not look up hostnames. (Useful if DNS is not functioning properly.)

-p port

Set base UDP port number used for probe packets to port. Default is (decimal) 33434.

-q n

Set number of probe packets for each time-to-live setting to the value n. Default is 3.

-r

Bypass normal routing tables and send directly to a host on an attached network.

-s src_addr

Use src_addr as the IP address that will serve as the source address in outgoing probe packets.

-t tos

Set the type-of-service in probe packets to tos (default 0). The value must be a decimal integer in the range 0 to 255.

-v

Verbose; received ICMP packets (other than TIME_EXCEEDED and PORT_UNREACHABLE) will be listed.

-w wait

Set time to wait for a response to an outgoing probe packet to wait seconds (default is 5).

-x

Toggle IP checksums, usually to turn them off. IP checksums are always calculated if -I is specified.

-z msecs

Set the delay between probes, in milliseconds. The default is 0.


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