Automated Presentation of directory utilities/short_timeout/

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       ~4Dgifts/toolbox/src/exampleCode/networking/short_timeout README



                        hrq:  host_responds_quickly

      Code that checks whether a remote host responds quickly, avoiding
      a long wait for a network timeout.


      A developer of a networked application may want to know if a host
      is present on the network before the application attempts to make
      use of some resource on that host.  The default network timeouts
      are suitable for use on a WAN, and may seem too lengthy for LAN
      users.

      The application may set a short timer, and if the timer expires
      before the network system call completes, the call will fail with
      errno set to EINTR.

      The example in this directory may be used as a model of how to
      interrupt a network system call with an alarm, or the example may
      be used without modification in your application.

      The function that does all the work is named host_responds_quickly,
      and it is found in file hrq.c.  The application that calls this
      function must #include header file hrq.h.  The file main.c contains
      a trivial driver that calls host_responds_quickly.

      An application written in a shell language may invoke the complete
      program hrq.  There's an example of how this can be done in the
      Bourne shell in script file hrq.sh.

      Program hrq (and any other program calling host_responds_quickly)
      needs to be installed setuid to root.    In a root shell, type

                chown root.sys hrq
                chmod 4755 hrq
                mv hrq /usr/local/bin

Documentation

• README
• index.html