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STRCHG(1)           RISC/os Reference Manual            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 fol-
     lowed 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 con-
     tains a list of modules representing the desired configura-
     tion 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 confi-
     guration.

     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



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STRCHG(1)           RISC/os Reference Manual            STRCHG(1)



     mutually exclusive.

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

          strchg -h stty_ld

     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
          stty_ld
          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 stty_ld
     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 stty_ld pushed above the ports driver, it would pro-
     duce the following output:

          stty_ld
          ports

     The following command asks if stty_ld is on the stream

          strconf -m stty_ld

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

          yes

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.




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STRCHG(1)           RISC/os Reference Manual            STRCHG(1)



     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 condi-
     tions, including usage error or failure of an ioctl on the
     stream.

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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