tcpclient(1)

💅 NAME 💅

okay so we’re in the General Commands Manual and the main character is tcpclient(1) — she creates an outgoing TCP connection. that’s the whole assignment, bestie. periodt. 💅

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✨ SYNOPSIS ✨

tcpclient [ opts ] host port prog

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🌸 DESCRIPTION 🌸

okay so real talk: opts is a series of getopt-style options. host is one argument. port is one argument. prog consists of one or more arguments. got it? iconic. 🫶

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). yes, she’s setting the whole vibe up for you. ✨

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. slay.

if the server has several IP addresses, tcpclient tries each address in turn. she’s thorough like that. 🔥

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🎀 OPTIONS 🎀

general options

• -q — Quiet. do not print error messages. shhh. 🙈
• -Q — (Default.) Print error messages. yes, she will tell you what went wrong. 💀
• -v — Verbose. print error messages and status messages. she’s giving commentary. 👑

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). okay so that’s the timing tea. ⏳
• -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. she’s usually chill like that. 🦋
• -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. same energy. 🌈
• -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. don’t just assume she’ll keep doing it, bestie. 🫶
• -D — Never delay sending data; enable TCP_NODELAY. no waiting, no drama. 🔥

data-gathering options

• -h — (Default.) Look up the remote host name in DNS to set the environment variable $TCPREMOTEHOST. she’s nosy in a useful way. 👀
• -H — Do not look up the remote host name in DNS; remove the environment variable $TCPREMOTEHOST. bye-bye hostname lookup. 💅
• -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. noted. ⭐
• -r — (Default.) Attempt to obtain $TCPREMOTEINFO from the remote host. she’s trying to get the info. 💖
• -R — Do not attempt to obtain $TCPREMOTEINFO from the remote host. no info-hunting today. 🙅‍♀️
• -t n — Give up on the $TCPREMOTEINFO connection attempt after n seconds. Default: 26. clock’s ticking, bestie. ⏰

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🦋 SEE ALSO 🦋

• 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)

and the website moment:

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

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xoxo, signed sealed delivered: it’s tcpclient(1) in the footer, no extra source/version/date line to spill — that’s the whole cute sign-off, bestie 🫶💜