---
name: "tcpclient"
section: "1"
platform: "linux"
package: "ucspi-tcp"
version: "1:0.88-13"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/tcpclient"
---

# tcpclient(1)

creates an outgoing TCP connection.

## NAME

tcpclient - creates an outgoing TCP connection.

## SYNOPSIS

**tcpclient** \[ *opts* \] *host* *port* *prog*

## DESCRIPTION

*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)](/tcp-environ/5.md) ).

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)](/tcpclient/1.md) 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.

## SEE ALSO

[tcpserver(1)](/tcpserver/1.md), [tcprules(1)](/tcprules/1.md), [tcprulescheck(1)](/tcprulescheck/1.md), [argv0(1)](/argv0/1.md), [fixcrio(1)](/fixcrio/1.md), [recordio(1)](/recordio/1.md), [rblsmtpd(1)](/rblsmtpd/1.md), who@(1), date@(1), finger@(1), http@(1), [tcpcat(1)](/tcpcat/1.md), [mconnect(1)](/mconnect/1.md), [tcp-environ(5)](/tcp-environ/5.md)

http://cr.yp.to/ucspi-tcp.html