tcpclient - creates an outgoing TCP connection.
tcpclient [ opts ] host port
prog
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.
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.
tcpserver(1), tcprules(1), tcprulescheck(1), argv0(1), fixcrio(1),
recordio(1), rblsmtpd(1), who@(1), date@(1), finger@(1), http@(1),
tcpcat(1), mconnect(1), tcp-environ(5)
http://cr.yp.to/ucspi-tcp.html