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#Command line interface: osm4j-utils

##Setup

osm4j also contains a command line interface for performing data manipulation tasks. To get started, check out the osm4j-utils repository:

git clone git@github.com:topobyte/osm4j-utils.git

After that, cd to the checked out repository (cd osm4j-utils) and build the project:

gradle createRuntime

There are a number of executables in the scripts subdirectory. To run the tool OsmCat, just type

./scripts/OsmCat

Alternatively, you can also add the scripts directory to your PATH variable:

export PATH=$PATH:/path/to/osm4j-utils/scripts

Afterwards you will be able to run the scripts directly. Make this permament, by adding it to your shell configuration.

##Examples

Get some data

Most operations are file based, so we will need some local data to work on:

wget -O berlin.pbf http://download.geofabrik.de/europe/germany/berlin-latest.osm.pbf

Basics: OsmCount and OsmCat

Now you can use the OsmCount tool to count the number of elements in the file:

OsmCount -input-format pbf -input berlin.pbf

Here's the output:

nodes:            4003479
ways:             612717
ways (closed):    468693
waynodes:         4848787
relations:        8296
relation members: 185542

Most commands support an input-format argument to specify the file format (xml, pbf, tbo). The input argument usually tells the tools where to read data from. In many tools the input argument is optional and if not specified, it will read from standard input.

Hence you can use Unix pipes to chain input and output. For example, the previous example can also be executed like this using the standard tool cat:

cat berlin.pbf | OsmCount -input-format pbf

Similar to the input and input-format arguments, many tools support output and output-format arguments.

For example this command will write the contents of the PBF file to another file in XML format:

OsmCat -input-format pbf -input berlin.pbf -output-format xml -output berlin.osm.xml

The output file will be about one gigabyte of data, so you may want to skip the previous command.

As with the input argument, the output argument is usually optional. If omitted, output will go to standard output, i.e. the console.

Again we can combine this with Unix pipes. For example, to browse the PBF file in XML format using less use this:

OsmCat -input-format pbf -input berlin.pbf -output-format xml | less

Filtering data

To filter data based on element tags you can use the OsmTagFilter command. For example, to extract all museums in Berlin and store them in an XML file, execute this:

OsmTagFilter -input-format pbf -input berlin.pbf -key tourism -value museum -output-format xml -output museums.osm.xml

We could also use Unix pipes and stream redirection for input and output:

cat berlin.pbf | OsmTagFilter -input-format pbf -key tourism -value museum -output-format xml > museums.osm.xml

Hence, commands can also easily be chained. If you just want to get some info about the number of museums, try this:

OsmTagFilter -input-format pbf -input berlin.pbf -key tourism -value museum -output-format pbf | OsmCount -input-format pbf

The results:

nodes:            100
ways:             78
ways (closed):    78
waynodes:         1224
relations:        11
relation members: 51
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