File: telltime.sh
   1 #!/bin/sh
   2 
   3 # The MIT License (MIT)
   4 #
   5 # Copyright (c) 2026 pacman64
   6 #
   7 # Permission is hereby granted, free of charge, to any person obtaining a copy
   8 # of this software and associated documentation files (the "Software"), to deal
   9 # in the Software without restriction, including without limitation the rights
  10 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11 # copies of the Software, and to permit persons to whom the Software is
  12 # furnished to do so, subject to the following conditions:
  13 #
  14 # The above copyright notice and this permission notice shall be included in
  15 # all copies or substantial portions of the Software.
  16 #
  17 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  20 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  23 # SOFTWARE.
  24 
  25 
  26 # telltime [port]
  27 #
  28 # Start a TCP server which always replies with the current local date/time as
  29 # a plain-text line.
  30 
  31 
  32 case "$1" in
  33     -h|--h|-help|--help)
  34         awk '/^# +telltime /, /^$/ { gsub(/^# ?/, ""); print }' "$0"
  35         exit 0
  36     ;;
  37 esac
  38 
  39 # if [ $# -eq 0 ]; then
  40 #     awk '/^# +telltime /, /^$/ { gsub(/^# ?/, ""); print }' "$0"
  41 #     exit 0
  42 # fi
  43 
  44 gawk -v port="$1" '
  45     BEGIN {
  46         if (port == "") {
  47             print "you forgot the port number" > "/dev/stderr"
  48             exit 1
  49         }
  50 
  51         if (port < 1 || port > 65535) {
  52             printf("%s is an invalid port number\n", port) > "/dev/stderr"
  53             exit 1
  54         }
  55 
  56         server = sprintf("/inet/tcp/%d/0/0", port)
  57         PROCINFO[server, "READ_TIMEOUT"] = 200
  58 
  59         msg = "current date and time on telnet://localhost:%d\n"
  60         printf(msg, port) > "/dev/stderr"
  61 
  62         while (1) {
  63             print strftime("%Y-%m-%d %H:%M:%S") |& server
  64             close(server)
  65         }
  66 
  67         exit
  68     }
  69 '