strchg(1M)

NAME

strchg, strconf — change or query stream configuration

SYNOPSIS

strchg -h module1 [, module2]...

strchg -p [ -a|-u module]

strchg -f file

strconf

strconf -t

strconf -m module

DESCRIPTION

The strchg and strconf commands are used to change 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 superuser or owner of a STREAMS device may alter the configuration of that stream.

strchg Options

The strchg command uses the following options:

-h module1[,module2] ...: strchg pushes modules onto a stream. The modules are pushable STREAMS modules as defined by module1, module2, and so on. The modules are pushed in order. That is, module1 is pushed first, module2 is pushed second, etc.
-p: With the -p option alone, strchg pops the topmost module from the stream.
-a: With the -p and -a options, all the modules above the topmost driver are popped.
-u module: With the -p and -u module options, all modules above but not including module are popped off the stream.

The -a and -u options are mutually exclusive.

-f file: 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.

strconf Options

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 in 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.

The strconf command uses the following options:

-t: Only the topmost module (if one exists) is printed.
-m module: strconf checks if the named module is present on the stream. If so, 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.

Notes

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

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.

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 be superuser.

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 only has 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

FILES

/usr/lib/nls/msg/C/strchg.cat: NLS catalogs
/usr/lib/nls/msg/C/strconf.cat: NLS catalogs