User Commands strchg(1)
NAME
strchg, strconf - change or query stream configuration
SYNOPSIS
strchg -h module1 [, module2...]
strchg -p [-a -u module]
strchg -f filename
strconf [-m -t 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 can
alter the configuration of that stream.
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.
OPTIONS
The following options apply to strchg and, -h, -f, and -p
are mutually exclusive.
-a
Pop all the modules above the topmost driver off the
stream. This option requires the -p option.
-f filename
Specify a filename 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. strchg determines the current configura-
tion of the stream and pop and push the necessary
modules in order to end up with the desired configura-
tion.
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User Commands strchg(1)
-h module1 [,module2...]
Mnemonic for push, 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.
-p
Mnemonic for pop, pops modules off the stream. With the
-p option alone, strchg pops the topmost module from the
stream.
-u module
All modules above, but not including module are popped
off the stream. This option requires the -p option.
The following options apply to strconf and, -m and -t are
mutually exclusive.
-m module Determine 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.
-t module Print only the topmost module (if one exists).
The -t and -m options are mutually exclusive.
EXAMPLES
Example 1 Using the strchg Command
The following command pushes the module ldterm on the stream
associated with the user's standard input:
example% strchg -h ldterm
The following command pops the topmost module from the
stream associated with /dev/term/24. The user must be the
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User Commands strchg(1)
owner of this device or the super user.
example% strchg -p < /dev/term/24
If the file fileconf contains the following:
ttcompat
ldterm
ptem
then the command
example% strchg -f fileconf
configures the user's standard input stream so that the
module ptem is pushed over the driver, followed by ldterm
and ttcompat 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 zs driver, it would produce
the following output:
ldterm
zs
The following command asks if ldterm is on the stream:
example% strconf -m ldterm
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User Commands strchg(1)
and produces the following output while returning an exit
status of 0:
yes
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWcsu
SEE ALSO
attributes(5), streamio(7I)
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
filename 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 fails. If the user does not
have read permissions on the stream and is not the super
user, the strconf command fails.
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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