tcpclient1

Usage

Overview

opts is a series of getopt-style options. host is one argument. port is one argument. prog consists of one or more arguments.

tcpclient attempts to connect to a TCP server. If it is successful, it runs prog, with descriptor 6 reading from the network and descriptor 7 writing to the network. It also sets up several environment variables (see tcp-environ(5) ).

The server's address is given by host and port. port may be a name from /etc/services or a number. host may be 0, referring to the local machine, or a dotted-decimal IP address, or a host name; it is fed through qualification using dns_ip4_qualify.

If the server has several IP addresses, tcpclient tries each address in turn.

Options

General options:

-q

Quiet. Do not print error messages.

-Q

(Default.) Print error messages.

-v

Verbose. Print error messages and status messages.

Connection options:

-T x+y

Give up on the connection attempt after x+y seconds. Default: 2+58. When a host has several IP addresses, tcpclient tries to connect to the first IP address, waits x seconds, tries to connect to the second IP address, waits x seconds, etc.; then it retries each address that timed out, waiting y seconds per address. You may omit +y to skip the second try. Before version 0.88, tcpclient(1) will use only x (default: 60).

-i localip

Use localip as the IP address for the local side of the connection; quit if localip is not available. Normally tcpclient lets the operating system choose an address.

-p localport

Use localport as the TCP port for the local side of the connection; quit if localport is not available. Normally tcpclient lets the operating system choose a port.

-d

Delay sending data for a fraction of a second whenever the remote host is responding slowly. This is currently the default, but it may not be in the future; if you want it, set it explicitly.

-D

Never delay sending data; enable TCP_NODELAY.

Data-gathering options:

-h

(Default.) Look up the remote host name in DNS to set the environment variable $TCPREMOTEHOST.

-H

Do not look up the remote host name in DNS; remove the environment variable $TCPREMOTEHOST.

-l localname

Do not look up the local host name in DNS; use localname for the environment variable $TCPLOCALHOST. A common choice for localname is 0.

-r

(Default.) Attempt to obtain $TCPREMOTEINFO from the remote host.

-R

Do not attempt to obtain $TCPREMOTEINFO from the remote host.

-t n

Give up on the $TCPREMOTEINFO connection attempt after n seconds. Default: 26.