slink(1M) MISC. REFERENCE MANUAL PAGES slink(1M)
NAME
slink - streams linker
SYNOPSIS
slink [ -v ] [ -p ] [ -u ] [ -f ] [ -c file ] [ func [arg1
arg2 ...]]
DESCRIPTION
slink is a STREAMS configuration utility which is used to
link together the various STREAMS modules and drivers
required for STREAMS TCP/IP. Input to slink is in the form
of a script specifying the STREAMS operations to be per-
formed. Input is normally taken from the file /etc/strcf.
The following options may be specified on the slink command
line:
-c file Use file instead of /etc/strcf.
-v Verbose mode (each operation is logged to stderr).
-p Don't use persistent links (i.e., slink will remain
in the background).
-f Don't use persistent links and don't fork (i.e.,
slink will remain in foreground).
-u Unlink persistent links (i.e., shut down network).
The configuration file contains a list of functions, each of
which is composed of a list of commands. Each command is a
call to one of the functions defined in the configuration
file or to one of a set of built-in functions. Among the
built-in functions are the basic STREAMS operations open,
link, and push, along with several TCP/IP-specific func-
tions.
slink processing consists of parsing the input file, then
calling the user-defined function boot, which is normally
used to set up the standard configuration at boot time. If
a function is specified on the slink command line, that
function will be called instead of boot.
By default, slink establishes streams with persistent links
(IPLINK) and exits following the execution of the specified
function. If the -p flag is specified, slink establishes
streams with regular links (ILINK) and remains idle in the
background, holding open whatever file descriptors have been
opened by the configuration commands. If the -f flag is
specified, slink establishes streams with regular links
(ILINK) and remains in the foreground, holding open what-
ever file descriptors have been opened by the configuration
Last change: TCP/IP 1
slink(1M) MISC. REFERENCE MANUAL PAGES slink(1M)
commands.
A function definition has the following form:
function-name {
command1
command2
...
}
The syntax for commands is:
function arg1 arg2 arg3 ...
or
var = function arg1 arg2 arg3 ...
The placement of newlines is important: a newline must fol-
low the left and right braces and every command. Extra new-
lines are allowed, i.e. where one newline is required, more
than one may be used. A backslash (\) followed immediately
by a newline is considered equivalent to a space, i.e. may
be used to continue a command on a new line. The use of
other white space characters (spaces and tabs) is at the
discretion of the user, except that there must be white
space separating the function name and the arguments of a
command.
Comments are delimited by # and newline, and are considered
equivalent to a newline.
Function and variable names may be any string of characters
taken from A-Z, a-z, 0-9, and , except that the first char-
acter cannot be a digit. Function names and variable names
occupy separate name spaces. All functions are global and
may be forward referenced. All variables are local to the
functions in which they occur.
Variables are defined when they appear to the left of an
equals (=) on a command line; for example,
tcp = open /dev/tcp
The variable acquires the value returned by the command. In
the above example, the value of the variable tcp will be the
file descriptor returned by the open call.
Arguments to a command may be either variables, parameters,
or strings.
A variable that appears as an argument must have been
assigned a value on a previous command line in that func-
tion.
Parameters take the form of a dollar sign ($) followed by
one or two decimal digits, and are replaced with the
Last change: TCP/IP 2
slink(1M) MISC. REFERENCE MANUAL PAGES slink(1M)
corresponding argument from the function call. If a given
parameter was not specified in the function call, an error
results (e.g. if a command references $3 and only two argu-
ments were passed to the function, an execution error will
occur).
Strings are sequences of characters optionally enclosed in
double quotes ("). Quotes may be used to prevent a string
from being interpreted as a variable name or a parameter,
and to allow the inclusion of spaces, tabs, and the special
characters {, }, =, and #. The backslash (\) may also be
used to quote the characters {, }, =, #, ", and \ individu-
ally.
The following built-in functions are provided by slink:
open path Open the device specified by pathname
path. Returns a file descriptor
referencing the open stream.
link fd1 fd2 Link the stream referenced by fd2
beneath the stream referenced by fd1.
Returns the link identifier associated
with the link. Unless the -f or -p
flag is specified on the command line,
the streams will be linked with per-
sistent links. Note: fd2 cannot be
used after this operation.
push fd module Push the module module onto the stream
referenced by fd.
sifname fd link name Send a SIOCSIFNAME (set interface
name) ioctl down the stream referenced
by fd for the link associated with
link identifier link specifying the
name name.
unitsel fd unit Send a IFUNITSEL (unit select) ioctl
down the stream referenced by fd
specifying unit unit.
dlattach fd unit Send a DLATTACHREQ message down the
stream referenced by fd specifying
unit unit.
initqp path qname lowat hiwat ...
Send an INITQPARMS (initialize queue
parameters) ioctl to the driver
corresponding to pathname path. qname
specifies the queue for which the low
and high water marks will be set, and
Last change: TCP/IP 3
slink(1M) MISC. REFERENCE MANUAL PAGES slink(1M)
must be one of:
hd stream head
rq read queue
wq write queue
muxrq
multiplexor read queue
muxwq
multiplexor write queue
lowat and hiwat specify the new low
and high water marks for the queue.
Both lowat and hiwat must be present.
To change only one of these parame-
ters, the other may be replaced with a
dash (-). Up to five qname lowat
hiwat triplets may be present.
strcat str1 str2 Concatenate strings str1 and str2 and
return the resulting string.
return val Set the return value for the current
function to val.
Note: executing a return command does
not terminate execution of the current
function.
FILES
/etc/strcf
SEE ALSO
strcf(4)
Last change: TCP/IP 4