strchg(1)                USER COMMANDS                  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)                USER COMMANDS                  strchg(1)



     mutually exclusive.

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

          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  pro-
     duce 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



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strchg(1)                USER COMMANDS                  strchg(1)



     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 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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