mirror of https://github.com/octoleo/lsyncd.git
284 lines
7.2 KiB
Markdown
284 lines
7.2 KiB
Markdown
---
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layout: default
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title: "Example: Auto-Image-Magic"
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tab: "manual/examples"
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---
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This [example](..) is a layer 1 script to make a special "magic" directory in which image files will be converted automatically therein.
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The full script:
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{% highlight lua %}
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local formats = { jpg = true, gif = true, png = true }
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convert = {
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delay = 0,
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maxProcesses = 99,
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action = function(inlet)
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local event = inlet.getEvent()
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if event.isdir then
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-- ignores events on dirs
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inlet.discardEvent(event)
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return
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end
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-- extract extension and basefilename
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local p = event.pathname
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local ext = string.match(p, ".*%.([^.]+)$")
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local base = string.match(p, "(.*)%.[^.]+$")
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if not formats[ext] then
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-- an unknown extenion
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log("Normal", "not doing something on ."..ext)
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inlet.discardEvent(event)
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return
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end
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-- autoconvert on create and modify
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if event.etype == "Create" or event.etype == "Modify" then
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-- builds one bash command
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local cmd = ""
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-- do for all other extensions
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for k, _ in pairs(formats) do
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if k ~= ext then
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-- excludes files to be created, so no
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-- followup actions will occur
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inlet.addExclude(base..'.'..k)
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if cmd ~= "" then
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cmd = cmd .. " && "
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end
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cmd = cmd..
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'/usr/bin/convert "'..
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event.source..p..'" "'..
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event.source..base..'.'..k..
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'" || /bin/true'
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end
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end
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log("Normal", "Converting "..p)
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spawnShell(event, cmd)
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return
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end
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-- deletes all formats if you delete one
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if event.etype == "Delete" then
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-- builds one bash command
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local cmd = ""
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-- do for all other extensions
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for k, _ in pairs(formats) do
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if k ~= ext then
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-- excludes files to be deleted, so no
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-- followup actions will occur
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inlet.addExclude(base..'.'..k)
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if cmd ~= "" then
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cmd = cmd .. " && "
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end
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cmd = cmd..
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'rm "'..event.source..base..'.'..k..
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'" || /bin/true'
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end
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end
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log("Normal", "Deleting all "..p)
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spawnShell(event, cmd)
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return
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end
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-- ignores other events.
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inlet.discardEvent(event)
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end,
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-----
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-- Removes excludes when convertions are finished
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--
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collect = function(event, exitcode)
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local p = event.pathname
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local ext = string.match(p, ".*%.([^.]+)$")
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local base = string.match(p, "(.*)%.[^.]+$")
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local inlet = event.inlet
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if event.etype == "Create" or
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event.etype == "Modify" or
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event.etype == "Delete"
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then
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for k, _ in pairs(formats) do
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inlet.rmExclude(base..'.'..k)
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end
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end
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end,
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}
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sync{convert, source="magicdir", recursive=false}
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{% endhighlight %}
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This creates a local table of all supported file formats. The file formats are used as keys.
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{% highlight lua %}
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local formats = { jpg=true, gif=true, png=true, }
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{% endhighlight %}
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Configures actions to be instant and there is unlimits the amount the conversion to be done at once. Well not unlimited but set the limit pretty high.
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{% highlight lua %}
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convert = {
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delay = 0,
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maxProcesses = 99,
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{% endhighlight %}
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This script uses the _layer 1_ inlet interface altough it greps only single events and not lists. It does this instead of _layer 2_ as it needs to do common operations for all kind of events.
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{% highlight lua %}
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action = function(inlet)
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local event = inlet.getEvent()
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{% endhighlight %}
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Ignores directories. As using _layer 1_ it has to explicitly discard events it does not spawn actions for.
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{% highlight lua %}
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if event.isdir then
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-- ignores events on dirs
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inlet.discardEvent(event)
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return
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end
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{% endhighlight %}
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Uses Lua string patterns to extract the file extension from the rest - here called base.
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{% highlight lua %}
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-- extract extension and basefilename
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local p = event.pathname
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local ext = string.match(p, ".*%.([^.]+)$")
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local base = string.match(p, "(.*)%.[^.]+$")
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{% endhighlight %}
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Looks the extension up in the formats table. This can be done, since formats are keys in that table. If not an image format it bails out.
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{% highlight lua %}
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if not formats[ext] then
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-- an unknown extenion
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log("Normal", "not doing something on ."..ext)
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inlet.discardEvent(event)
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return
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end
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{% endhighlight %}
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Following actions will done on "Create" and "Modify" events.
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{% highlight lua %}
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-- autoconvert on create and modify
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if event.etype == "Create" or event.etype == "Modify" then
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{% endhighlight %}
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This script builds a bash command using a string.
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{% highlight lua %}
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-- builds one bash command
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local cmd = ""
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{% endhighlight %}
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It iterates for all image formats and excludes the one which is the source image.
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{% highlight lua %}
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-- do for all other extensions
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for k, _ in pairs(formats) do
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if k ~= ext then
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{% endhighlight %}
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This is a little trick. It creates Exclusions for the converted images. As this images are not placed in a target directory but right next to the source image in the source directory they would otherwise trigger Create actions as well.
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{% highlight lua %}
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-- excludes files to be created, so no
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-- followup actions will occur
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inlet.addExclude(base..'.'..k)
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{% endhighlight %}
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And for every image to be converted adds the calls to the arguments. It uses ```" || /bin/true "``` to let the shell continue if one conversion fails. In that it chains the conversion with '&&' they will be called sequentially.
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{% highlight lua %}
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if cmd ~= "" then
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cmd = cmd .. " && "
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end
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cmd = cmd..
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'/usr/bin/convert "'..
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event.source..p..'" "'..
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event.source..base..'.'..k..
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'" || /bin/true'
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{% endhighlight %}
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And eventually it spawns the shell doing the conversions and is finished.
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{% highlight lua %}
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end
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end
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log("Normal", "Converting "..p)
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spawnShell(event, cmd)
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return
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end
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{% endhighlight %}
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For deletions it does technically something similar, but it deletes all other file formats of the image.
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{% highlight lua %}
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-- deletes all formats if you delete one
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if event.etype == "Delete" then
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-- builds one bash command
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local cmd = ""
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-- do for all other extensions
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for k, _ in pairs(formats) do
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if k ~= ext then
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-- excludes files to be deleted, so no
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-- followup actions will occur
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inlet.addExclude(base..'.'..k)
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if cmd ~= "" then
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cmd = cmd .. " && "
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end
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cmd = cmd..
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'rm "'..event.source..base..'.'..k..
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'" || /bin/true'
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end
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end
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log("Normal", "Deleting all "..p)
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spawnShell(event, cmd)
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return
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end
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{% endhighlight %}
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and not to forget to nicely discard all other events.
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{% highlight lua %}
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-- ignores other events.
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inlet.discardEvent(event)
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end,
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{% endhighlight %}
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collect is called when the conversions finished. It will remove the temporary excludes again.
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{% highlight lua %}
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-----
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-- Removes excludes when convertions are finished
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--
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collect = function(event, exitcode)
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local p = event.pathname
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local ext = string.match(p, ".*%.([^.]+)$")
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local base = string.match(p, "(.*)%.[^.]+$")
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local inlet = event.inlet
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if event.etype == "Create" or
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event.etype == "Modify" or
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event.etype == "Delete"
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then
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for k, _ in pairs(formats) do
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inlet.rmExclude(base..'.'..k)
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end
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end
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end,
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{% endhighlight %}
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And finally use the configuration to watch "magicdir".
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{% highlight lua %}
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sync{convert, source="magicdir", recursive=false}
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{% endhighlight %}
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