~! is a directive from the glory days of Unix computing. Back when only research institutions, universities or government agencies had access to the Internet, the less privileged among us had only one alternative for networking computers together, uucp and its supporting communications utilities. When you were connected to a remote system via the cu utility, you could escape back to your home system, without dropping the connection, with the ~! directive. This was invaluable in the age when X11 and AT&T's layers windowing utilities were still only in use in big-budget IT shops.

From the man page:

     Commands

     The transmit process interprets the following user initiated
     commands:

     ~. Terminates the conversation.

   ~! Escapes to an interactive shell on the local system.

   ~!cmd...
      Runs cmd on the local system (via sh -c).

     ~$cmd...
          Runs cmd locally and send its output to the remote
          system.

     ~%cd Changes the directory on the local system. Note: ~!cd
          will cause the command to be run by a sub-shell, prob-
          ably not what was intended.

     ~%take from [to]
          Copies file from (on the remote system) to file to on
          the local system. If to is omitted, the from argument
          is used in both places.


     ~%put from [to]
          Copies file from (on local system) to file to on
          remote system. If to is omitted, the from argument is
          used in both places.

     ~~line
          Sends the line ~ line to the remote system.

     ~%break
          Transmits a BREAK to the remote system (which can
          also be specified as ~%b).

     ~%debug
          Toggles the -d debugging option on or off (which can
          also be specified as ~%d).

     ~t Prints the values of the termio structure variables
          for the user's terminal (useful for debugging).


     ~l Prints the values of the termio structure variables
          for the remote communication line (useful for debug-
          ging).

     ~%ifc Toggles between DC3/DC1 input control protocol and no
          input control. This is useful when the remote system
          does not respond properly to the DC3 and DC1 charac-
          ters (can also be specified as ~%nostop).


     ~%ofc Toggles the output flow control setting. When
          enabled, outgoing data may be flow controlled by the
          remote host (can also be specified as ~%noostop).


     ~%divert
          Allows/disallows unsolicited diversions. That is,
          diversions not specified by ~%take.


     ~%old Allows/disallows old style syntax for received diver-
          sions.

     ~%nostop
          Same as ~%ifc.

     The receive process normally copies data from the remote
     system to the standard output of the local system. It may
     also direct the output to local files.






Therefore, what better domain for hosting home pages than tildebang, the command that, wherever you were in the dawn of networking, always brought you home? It's surprising the domain wasn't already taken.

Copyright (except man page excerpt) © 2007 David Breneman, Rosedale Audio Productions