ARTICLE: "io.launcher.command""Specifying a command"
"The " { $snippet "command" } " slot of a " { $link process } " can contain either a string or a sequence of strings. In the first case, the string is processed in an operating system-specific manner. In the second case, the first element is a program name and the remaining elements are passed to the program as command-line arguments.";
ARTICLE: "io.launcher.detached""Running processes in the background"
"By default, " { $link run-process } " waits for the process to complete. To run a process without waiting for it to finish, set the " { $snippet "detached" } " slot of a " { $link process } ", or use the following word:"
"The " { $snippet "environment" } " slot of a " { $link process } " contains an association mapping environment variable names to values. The interpretation of environment variables is operating system-specific."
"The " { $snippet "environment-mode" } " slot controls how the environment of the current Factor instance is composed with the value of the " { $snippet "environment" } " slot:"
{ $subsection +prepend-environment+ }
{ $subsection +replace-environment+ }
{ $subsection +append-environment+ }
"The default value is " { $link +append-environment+ } ".";
"To specify redirection, set the " { $snippet "stdin" } ", " { $snippet "stdout" } " and " { $snippet "stderr" } " slots of a " { $link process } " to one of the following values:"
{ $list
{ { $link f } " - default value; the stream is either inherited from the current process, or is a " { $link <process-stream> } " pipe" }
{ { $link +closed+ } " - the stream is closed; reads will return end of file and writes will fails" }
{ { $link +stdout+ } " - a special value for the " { $snippet "stderr" } " slot only, indicating that the standard output and standard error streams should be merged" }
{ "a path name - the stream is sent to the given file, which must exist for input and is created automatically on output" }
{ "a file stream or a socket - the stream is connected to the given Factor stream, which cannot be used again from within Factor and must be closed after the process has been started" }
ARTICLE: "io.launcher.priority""Setting process priority"
"The priority of the child process can be set by storing one of the below symbols in the " { $snippet "priority" } " slot of a " { $link process } " tuple:"
{ $list
{ $link +lowest-priority+ }
{ $link +low-priority+ }
{ $link +normal-priority+ }
{ $link +high-priority+ }
{ $link +highest-priority+ }
}
"The default value is " { $link f } ", which denotes that the child process should inherit the current process priority.";
{ $description "Creates an object which may be stored in the " { $snippet "stdout" } " or " { $snippet "stderr" } " slot of a " { $link process } " instance." } ;
{ $description "Possible value of " { $snippet "environment-mode" } " slot of a " { $link process } "."
$nl
"If this value is set, the child process environment consists of the value of the " { $snippet "environment" } " slot together with the current environment, with entries from the current environment taking precedence."
"This is used in situations where you want to spawn a child process with some default environment variables set, but allowing the user to override these defaults by changing the environment before launching Factor." } ;
{ $description "Possible value of " { $snippet "environment-mode" } " slot of a " { $link process } "."
$nl
"The child process environment consists of the current environment together with the value of the " { $snippet "environment" } " key, with entries from the " { $snippet "environment" } " key taking precedence."
"The " { $snippet "timeout" } " slot of a " { $link process } " can be set to a " { $link duration } " specifying a maximum running time for the process. If " { $link wait-for-process } " is called and the process does not exit before the duration expires, it will be killed.";
{ $description "Combines the current environment with the value of the " { $snippet "environment" } " slot of the " { $link process } " using the " { $snippet "environment-mode" } " slot." } ;
{ $description "Launches a process. The object can either be a string, a sequence of strings or a " { $link process } ". See " { $link "io.launcher.descriptors" } " for details." }
{ $contract "Launches a process without waiting for it to complete. The object can either be a string, a sequence of strings or a " { $link process } ". See " { $link "io.launcher.descriptors" } " for details." }
{ $error-description "Thrown by " { $link try-process } " if the process exited with a non-zero status code." } ;
HELP:try-process
{ $values { "desc""a launch descriptor" } }
{ $description "Launches a process and waits for it to complete. If it exits with a non-zero status code, throws a " { $link process-failed } " error." } ;
{ $description "Launches a process and redirects its input and output via a pair of pipes which may be read and written as a stream of the given encoding." } ;
{ $values { "process" process } { "status"object } }
{ $description "If the process is still running, waits for it to exit, otherwise outputs the status code immediately. Can be called multiple times on the same process." }
{ $notes "The status code is operating system specific; it may be an integer, or another object (the latter is the case on Unix if the process was killed by a signal). However, one cross-platform behavior code can rely on is that a status code of 0 indicates success." } ;
"Words which launch processes can take either a command line string, a sequence of command line arguments, or a " { $link process } "."
$nl
"Strings and string arrays are wrapped in a new empty " { $link process } " with the " { $snippet "command" } " slot set. This covers basic use-cases where no launch parameters need to be set."
$nl
"A " { $link process } " instance can be created directly and passed to launching words for more control. It must be a fresh instance which has never been spawned before. To spawn a process several times from the same descriptor, " { $link clone } " the descriptor first.";
ARTICLE: "io.launcher.lifecycle""The process lifecycle"
"The " { $link process } " instance output by launching words contains all original slot values in addition to the " { $snippet "handle" } " slot, which indicates the process is currently running."
