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Diffstat (limited to 'doc/direvent.texi')
| -rw-r--r-- | doc/direvent.texi | 57 |
1 files changed, 43 insertions, 14 deletions
diff --git a/doc/direvent.texi b/doc/direvent.texi index 6781ac5..e307bf2 100644 --- a/doc/direvent.texi +++ b/doc/direvent.texi @@ -152,14 +152,14 @@ directories with a set of events and instructs @command{direvent} to run a specified external command when any of these events occur in any of these directories. This external command (called a @dfn{handler}) can obtain information about the event that triggered it from the environment variables, or from its command line. Watchers are defined in the configuration file, which -@command{direvent} reads at startup. This file has a simple and easy -to use syntax. +@command{direvent} reads at startup. The following outlines its +syntax: Three types of comments are allowed: inline comments, that begin with a @samp{#} or @samp{//} and extend to the end of line, and multi-line comments, which comprise everything enclosed between @samp{/*} and @samp{*/}. Comments and empty lines are ignored. Whitespace characters are ignored as well, except as they serve to separate @@ -176,13 +176,13 @@ Adjacent quoted strings are concatenated. A configuration statement consists of a keyword and value separated by any amount of whitespace and is terminated with a semicolon. A block statement is a collection of statements enclosed in curly braces. @cindex watcher declaration, summary -The following block statement declares a watcher: +A watcher is declared using the following block statement: @example @group watcher @{ path @var{pathname} [recursive [@var{level}]]; file @var{pattern-list}; @@ -205,12 +205,21 @@ the supplied @var{command-line} will be executed. Each directory defined with the @code{recursive} keyword will be watched recursively. This means that for each subdirectory created in it, @command{direvent} will install a watcher similar to that of its parent directory. Optional @var{level} statement can be used to set up a cut-off nesting level, beyond which the recursive operation is disabled. +It is a common practice for the @code{path} statement to refer to a +directory. However, it is not a requirement. The @var{pathname} +argument can as well point to any other type of +file@footnote{Obviously, the @samp{recursive} keyword is valid only if +@var{pathname} is a directory.}. Moreover, it is not required to +exist, either. If it does not, @GNUDIREVENT{} will remember the +watcher definition and will set it up when the @var{pathname} is +eventually created.@footnote{@xref{path}, for a detailed description.} + The rest of statements are optional. The @code{file} statement instructs @GNUDIREVENT{} to react only if the event concerned the file whose name matches one of the patterns given in its argument. The @code{user} statement can be used to execute the @var{command-line} as the user @var{name} (provided, of course, that @command{direvent} is started with root privileges). The @@ -878,13 +887,13 @@ syslog @{ @node watcher @section Watcher @cindex watcher, complete description The @samp{watcher} statement configures a single event watcher. A watcher can control several events in multiple pathnames. Any number of @code{watcher} -statements is allowed in the configuration file, each one of them declaring +statements is allowed in the configuration file, each of them declaring a separate watcher. @cindex watcher declaration @example @group watcher @{ @@ -899,24 +908,44 @@ watcher @{ @} @end group @end example The statements within a @code{watcher} block are: +@anchor{path} @deffn {Config} path @var{pathname} [recursive [@var{number}]] Defines a pathname to watch. The @var{pathname} argument must be the -name of an existing directory in the file system. The watcher will -watch events occurring for all files within that directory. If the -optional @code{recursive} clause is specified, this directory will be -watched recursively, i.e. when any subdirectory is created in it, -@command{direvent} will set up a watcher for files in this -subdirectory. This new watcher will be an exact copy of the parent -watcher, excepting for the pathnames. The optional @var{number} -parameter defines a cut-off nesting level for recursive watching. If -supplied, the recursive behaviour will apply only to the directories -that are nested below that level. +name of a directory or file in the file system. If @var{pathname} +refers to a directory, the watcher will watch events occurring for all +files within that directory. If the optional @code{recursive} clause +is specified, this directory will be watched recursively, i.e. when +any subdirectory is created in it, @command{direvent} will set up a +watcher for files in this subdirectory. This new watcher will be an +exact copy of the parent watcher, excepting for the pathnames. The +optional @var{number} parameter defines a cut-off nesting level for +recursive watching. If supplied, the recursive behaviour will apply +only to the directories that are nested below that level. + +If @var{pathname} refers to a regular file, the changes to that file +will be monitored. Obviously, in that case the @samp{recursive} +keyword makes no sense. If present, it will be silently ignored. + +@cindex sentinel +If the @var{pathname} does not exist, @GNUDIREVENT{} will defer +setting up the watcher until it is created. In order to do so, +it will find the longest directory prefix that exists in the file +system and will construct a @dfn{sentinel watcher} to monitor +creation of the next directory component. When this component is +created, the sentinel wakes up to set up a similar watcher for the +next directory component. Once it is done, the sentinel removes +itself. This process continues until the @var{pathname} is eventually +created. When it happens, the last sentinel will activate the +configured watcher. + +These actions are performed in reverse order upon removal of +@var{pathname} or any of its trailing directory components. Any number of @code{path} statements can appear in a @code{watcher} block. At least one @code{path} must be defined. @end deffn @deffn {Config} file @var{regexp-list} |