Network services

The configuration language

The language in which configuration scripts are written consists of a sequence of commands, each of which is interpreted separately. The following reserved keywords are defined: assign, push, pop, runwait, and run. The comment character is ``#''. Blank lines are not significant.

NOTE: The maximum line length in a command script is 1024 characters.

assign variable=value: Used to define environment variables. variable is the name of the environment variable and value is the value to be assigned to it. The value assigned must be a string constant; no form of parameter substitution is available. value may be quoted. The quoting rules are those used by the shell for defining environment variables. assign will fail if space cannot be allocated for the new variable or if any part of the specification is invalid.
push module1 [, module2, module3, ...]: Used to push STREAMS modules onto the stream designated by fd (see doconfig(3iac)). module1 is the name of the first module to be pushed, module2 is the name of the second module to be pushed, and so on. The command will fail if any of the named modules cannot be pushed. If a module cannot be pushed, the subsequent modules on the same command line will be ignored and modules that have already been pushed will be popped.
pop [module]: Used to pop STREAMS modules off the designated stream. If pop is invoked with no arguments, the top module on the stream is popped. If an argument is given, modules will be popped one at a time until the named module is at the top of the stream. If the named module is not on the designated stream, the stream is left as it was and the command fails. If module is the special keyword ``ALL'', then all modules on the stream will be popped. Note that only modules above the topmost driver are affected.
runwait command: The runwait command runs a command and waits for it to complete. command is the pathname of the command to be run. The command is run with /bin/sh -c prepended to it; shell scripts may thus be executed from configuration scripts. The runwait command will fail if command cannot be found or cannot be executed, or if command exits with a non-zero status.
run command: The run command is identical to runwait except that it does not wait for command to complete. command is the pathname of the command to be run. run will not fail unless it is unable to create a child process to execute the command.

Although they are syntactically indistinguishable, some of the commands available to run and runwait are interpreter built-in commands. Interpreter built-ins are used when it is necessary to alter the state of a process within the context of that process. The doconfig interpreter built-in commands are similar to the shell special commands and, like these, they do not spawn another process for execution. See sh(1). The initial set of built-in commands is:

cd
ulimit
umask