How to write daemon? Post: 90074

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Top Forums Programming How to write daemon? Post 90074 by Perderabo on Friday 18th of November 2005 01:33:34 AM

11-18-2005

Administrator Emeritus

I guess that either technique presented in those links is good enough, but I have to say that there is some room for improvement. Both of these techniques are relying on the parent to not make strange mistakes prior to invoking the daemon. We can do a better job of protecting ourself from a insane or hostile parent. By using two forks separated by a setsid() we can create a process that is guaranteed to not have a controlling terminal or even have the ability to accidentally acquire one. I kinda like the idea of closing all possible fd's, but using gettablesize sabotages the idea. gettablesize is basicly a getrlimit(RLIMIT_NOFILE) and is returning the soft limit. You can open a file and then set the soft limit lower...the file won't close or anything. And if the total number of open file is low, you can still open new files. Using sysconf() can avoid that.

Here is a link that gets all of this right 1.7 How do I get my program to act like a daemon? This link is from the Usenet comp.unix.programmer FAQ. From the same FAQ, also see Daemon utility functions. In fact, see the entire FAQ. The whole thing is excellent, despite being a little dated.

Perderabo

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qt2kdoc

QT2KDOC(1)						     KDOC Documentation System							QT2KDOC(1)

NAME

       qt2kdoc -- Generates cross-reference file suitable for use with KDOC from Qt Toolkit HTML documentation.

SYNOPSIS

	       qt2kdoc [-u URL] [-o <destdir>] [-z] <path to qt html>

DESCRIPTION

       qt2kdoc generates a kdoc(1) cross-reference file from  the classes.html file that is included with the Qt GUI Toolkit HTML documentation.

       The resulting file can be used to cross-reference documentation generated with KDOC for other classes with the Qt HTML documentation.

OPTIONS

       --url <url>, -u <url>
	   The URL  by	which  the  Qt	documentation  can  be accessed.  This	will allow other libraries to link to the Qt documentation.

       --outdir <path>, -o <path>
	   The directory where the generated index file will be written.

       --compress, -z
	   Compress the generated index with gzip. KDOC can read these compressed index files.

EXAMPLES

	       qt2kdoc -u "http://www.mydomain/src/qthtml/" 
		       $HOME/web/src/qthtml

ENVIRONMENT

       KDOCLIBS
	   If set, it is used as the default output path. It is overridden by the --outdir option.

FILES

       classes.html, functions.html
	   The files from which information about the Qt library is read. They are parsed by qt2kdoc.

       qt.kdoc
	   A kdoc(1) cross-reference file that will be	generated  by qt2kdoc and can be used to link documentation generated by kdoc with the Qt
	   documentation.

SEE ALSO

       This script is a utility for kdoc(1).

BUGS

       Dependent on format of Qt documentation.

AUTHOR

       Sirtaj S. Kang <taj@kde.org>, 1998.

2.0a54								    2002-03-18								QT2KDOC(1)