strchg(1)                        UNIX System V                        strchg(1)


NAME
      strchg, strconf - change or query stream configuration

SYNOPSIS
      strchg -h module1[,module2 ...]
      strchg -p [-a | -u module]
      strchg -f file
      strconf [-t | -m module]

DESCRIPTION
      These commands are used to alter or query the configuration of the stream
      associated with the user's standard input.  The strchg command pushes
      modules on and/or pops modules off the stream.  The strconf command
      queries the configuration of the stream.  Only the super-user or owner of
      a STREAMS device may alter the configuration of that stream.

      With the -h option, strchg pushes modules onto a stream; it takes as
      arguments the names of one or more pushable streams modules.  These
      modules are pushed in order; that is, module1 is pushed first, module2 is
      pushed second, etc.

      The -p option pops modules off the stream.  With the -p option alone,
      strchg pops the topmost module from the stream.  With the -p and -a
      options, all the modules above the topmost driver are popped.  When the
      -p option is followed by -u module, then all modules above but not
      including module are popped off the stream.  The -a and -u options are
      mutually exclusive.

      With the -f option, the user can specify a file that contains a list of
      modules representing the desired configuration of the stream.  Each
      module name must appear on a separate line where the first name
      represents the topmost module and the last name represents the module
      that should be closest to the driver.  The strchg command will determine
      the current configuration of the stream and pop and push the necessary
      modules in order to end up with the desired configuration.

      The -h, -f and -p options are mutually exclusive.

      Invoked without any arguments, strconf prints a list of all the modules
      in the stream as well as the topmost driver.  The list is printed with
      one name per line where the first name printed is the topmost module on
      the stream (if one exists) and the last item printed is the name of the
      driver.  With the -t option, only the topmost module (if one exists) is
      printed.  The -m option determines if the named module is present on a
      stream.  If it is, strconf prints the message yes and returns zero.  If
      not, strconf prints the message no and returns a non-zero value.  The -t
      and -m options are mutually exclusive.

EXAMPLES
      The following command pushes the module ldterm on the stream associated
      with the user's standard input:



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strchg(1)                        UNIX System V                        strchg(1)


            strchg -h ldterm

      The following command pops the topmost module from the stream associated
      with /dev/term/24.  The user must be the owner of this device or the
      super-user.

            strchg -p < /dev/term/24

      If the file fileconf contains the following:

            compat
            ldterm
            ptem

      then the command

            strchg -f fileconf

      will configure the user's standard input stream so that the module ptem
      is pushed over the driver, followed by ldterm and compat closest to the
      stream head.

      The strconf command with no arguments lists the modules and topmost
      driver on the stream; for a stream that has only the module ldterm pushed
      above the ports driver, it would produce the following output:

            ldterm
            ports

      The following command asks if ldterm is on the stream

            strconf -m ldterm

      and produces the following output while returning an exit status of 0:

            yes

SEE ALSO
      streamio(7) in the Programmer's Guide: STREAMS.

DIAGNOSTICS
      strchg returns zero on success.  It prints an error message and returns
      non-zero status for various error conditions, including usage error, bad
      module name, too many modules to push, failure of an ioctl on the stream,
      or failure to open file from the -f option.

      strconf returns zero on success (for the -m or -t option, "success" means
      the named or topmost module is present).  It returns a non-zero status if
      invoked with the -m or -t option and the module is not present.  It
      prints an error message and returns non-zero status for various error
      conditions, including usage error or failure of an ioctl on the stream.



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strchg(1)                        UNIX System V                        strchg(1)


NOTES
      If the user is neither the owner of the stream nor the super-user, the
      strchg command will fail.  If the user does not have read permissions on
      the stream and is not the super-user, the strconf command will fail.

      If modules are pushed in the wrong order, one could end up with a stream
      that does not function as expected.  For ttys, if the line discipline
      module is not pushed in the correct place, one could have a terminal that
      does not respond to any commands.













































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