11 This class can be used to start child processes.
13 An instance of the class represents a child process.
14 You should use this class if you need to start an external program in LyX.
15 If you wish, you can have a callback function executed when the process
17 You can chose between three kinds of child processes:
18 1) System processes, which are initiated with the "system" call,
19 where the main thread waits for the system call to return.
20 2) Wait for child process, which are forked, but the main thread waits for
22 3) Don't wait, which are forked, but the main thread is not stopped.
23 The process can be considered a background process.
24 A timer will make sure that any callback function is called when
25 the child process ends.
27 Notice that any callback associated with a process is called whatever
28 the kind of child process.
34 System, // Uses system() which uses /bin/sh
35 Wait, // Uses fork() and execvp()
36 DontWait // Uses fork() and execvp()
39 /// Callback function gets commandline and return value from child
40 typedef void (*Callbackfct)(string cmd, int retval);
45 /** Generate instance and start child process.
46 The string "what" contains a commandline with arguments separated
48 When the requested program finishes, the callback-function is
49 called with the commandline and the return value from the program.
50 The instance is automatically added to a timer check if starttype
51 is DontWait (i.e. background execution). When a background child
52 finishes, the timer check will automatically call the callback
55 Systemcalls(Starttype how, string const & what, Callbackfct call = 0);
60 /** Start childprocess. "what" contains a command at system level.
61 * This is for reuse of the Systemcalls instance.
63 int startscript(Starttype how, string const & what,
64 Callbackfct call = 0);
66 /** gets PID of childprocess. Used by timer */
67 pid_t getpid() { return pid; }
70 void callback() { if (cbk) cbk(command, retval); }
72 /** Set return value. Used by timer */
73 void setRetValue(int r) { retval = r; }
75 /** Kill child prematurely.
76 First, a SIGHUP is sent to the child.
77 If that does not end the child process within "tolerance"
78 seconds, the SIGKILL signal is sent to the child.
79 When the child is dead, the callback is called.
81 void kill(int tolerance = 5);
83 /// Type of execution: system, wait for child or background
92 /// Process ID of child
95 /// Return value from child
104 /// Wait for child process to finish. Updates returncode from child.