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 performed. 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 functions.

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 (I_PLINK) and exits following the execution of the specified function. If the -p flag is specified, slink establishes streams with regular links (I_LINK) 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 (I_LINK) and remains in the foreground, holding open whatever file descriptors have been opened by the configuration 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 character 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 function.

Parameters take the form of a dollar sign ($) followed by one or two decimal digits, and are replaced with the 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 arguments 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 \ individually.

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 persistent 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 IF_UNITSEL (unit select) ioctl down the stream referenced by fd specifying unit unit.

dlattach fd unit Send a DL_ATTACH_REQ 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
                      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 parameters, 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)