|tcpclient(1)||General Commands Manual||tcpclient(1)|
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.
- Quiet. Do not print error messages.
- (Default.) Print error messages.
- Verbose. Print error messages and status messages.
- -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.
- 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.
- Never delay sending data; enable TCP_NODELAY.
- (Default.) Look up the remote host name in DNS to set the environment variable $TCPREMOTEHOST.
- 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.
- (Default.) Attempt to obtain $TCPREMOTEINFO from the remote host.
- Do not attempt to obtain $TCPREMOTEINFO from the remote host.
- -t n
- Give up on the $TCPREMOTEINFO connection attempt after n seconds. Default: 26.