****Simplest command line irc client - spartanIrcClient.tcl****

[ccbbaa] 20210520: I wrote this ~20 loc irc client just because we were discussing very simple irc clients in `#tcl` on `freenode.net` . It took about 30 minutes including testing using `tclircd` and then on `freenode`. The client responds to server pings properly and won't drop out because of that.

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#!/usr/bin/tclsh
#
# spartanIrcClient.tcl
#
# v0: simple irc client in 10loc or so - plp 20210520
# v0a: close application when remote closes socket
#
# sample session:
#
# $ ./spartanIrcClient.tcl
# :card.freenode.net NOTICE * :*** Looking up your hostname...
# :card.freenode.net NOTICE * :*** Checking Ident
# :card.freenode.net NOTICE * :*** Couldn't look up your hostname
# USER nic nic * * : descr
# NICK nicnic
# : lots of server output elided
# JOIN #somechannel
# WHO #somechannel
# PRIVMSG #somechannel hi, I'm a spartan irc client
# QUIT
# [press enter to exit the session]

set ::s [socket -async irc.freenode.net 6667]
fconfigure $::s -blocking 0 -buffering line -encoding binary -translation binary
fileevent $::s readable "readsock $s"
proc readsock {chan} {
  if {[gets $chan line] < 0} {
    if {[eof $chan]} {
      close $chan; puts "Remote closed socket. Quitting."; exit 0
    }
  } else {
    puts stdout $line; flush stdout
    if {[regexp {^PING :(.*)$} $line dummy server]} {
      puts $chan "PONG :$server"; puts "PONG :$server"
    }
  }
}
fconfigure stdin -blocking 0 -buffering line -encoding binary -translation binary
fileevent stdin readable "readstdin stdin"
proc readstdin {chan} {
  if {[gets $chan line] < 0} {
    if {[eof $chan]} {exit 0} ;# user issued ^D
  } else {
    if {[catch "puts $::s $line" err]} {exit 0}
  }
}
vwait forever
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