2015-08-09 23:58:03 +02:00
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# File {#file}
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2015-08-07 01:20:27 +02:00
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The `file` node-type can be used to log or replay sample values to disk.
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## Configuration
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Every `file` node supports the following settings:
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2015-08-09 23:58:03 +02:00
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#### `in`
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2015-08-07 01:20:27 +02:00
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2015-08-09 23:58:03 +02:00
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Specifies the path to a file which contains data for replaying.
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See below for a description of the file format.
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2015-08-07 01:20:27 +02:00
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2015-08-09 23:58:03 +02:00
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#### `out`
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2015-08-07 01:20:27 +02:00
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2015-08-09 23:58:03 +02:00
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Specifies the path to a file where samples will be written to.
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This setting allows to add special paceholders for time and date values.
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See [strftime(3)](http://man7.org/linux/man-pages/man3/strftime.3.html) for a list of supported placeholder.
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**Example**:
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out = "logs/measurements_%Y-%m-%d_%H-%M-%S.log"
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will create a file called: *path_of_working_directory*/logs/measurements_2015-08-09_22-20-50.log
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#### `file_mode`
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Specifies the mode which should be used to open the output file.
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See [open(2)](http://man7.org/linux/man-pages/man2/open.2.html) for an explanation of allowed values.
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The default value is `w+` which will start writing at the beginning of the file and create it in case it does not exist yet.
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#### `epoch_mode`
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This setting allows to select the behaviour of the following `epoch` setting.
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It can be used to adjust the point in time when the first value should be read.
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The behaviour of `epoch` is depending on the value of `epoch_mode`.
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- `epoch_mode = now`: The first value is read at *now* + `epoch` seconds.
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- `epoch_mode = relative`: The first value is read at *start* + `epoch` seconds.
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- `epoch_mode = absolute`: The first value is read at `epoch` seconds after 1970-01-01 00:00:00.
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#### `rate`
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By default `rate` has the value `0`. If the value is non-zero,
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2015-08-07 01:20:27 +02:00
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### Example
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@todo Add extract of example.conf
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## File Format
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This node-type uses a simple human-readable format to save samples:
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The format is similiar to a conventional CSV (comma seperated values) file.
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Every line in a file correspondents to a message / sample of simulation data.
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The columns of a line are seperated by whitespaces (tabs or spaces).
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The columns are defined as follows:
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1. Seconds in floating point format since 1970-01-01 00:00:00 (aka Unix epoch timestamp: `date +%s`).
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2. Sequence number
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3. Up to `MSG_VALUES` floating point values per sample. The values are seperated by whitespaces as well.
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### Example
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2015-08-09 23:58:03 +02:00
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This example shows a dump with three values per sample:
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1438959964.162102394 6 3.489760 -1.882725 0.860070
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1438959964.261677582 7 2.375948 -2.204084 0.907518
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1438959964.361622787 8 3.620115 -1.359236 -0.622333
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1438959964.461907066 9 5.844254 -0.966527 -0.628751
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1438959964.561499526 10 6.317059 -1.716363 0.351925
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1438959964.661578339 11 6.471288 -0.159862 0.123948
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1438959964.761956859 12 7.365932 -1.488268 -0.780568
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