usage:

java <Java options> <JOSM JVM options> -jar josm.jar <Post jar options> [file]

or

javaws https://josm.openstreetmap.de/download/josm.jnlp
javaws [options] [URL or path to josm.jnlp file]

Java 7 docs about javaws: ​http://docs.oracle.com/javase/7/docs/technotes/tools/share/javaws.html

Java options

-Xmx...m                                  Set maximum Java heap size in megabytes

For some tasks, JOSM has a large appetite for memory. On the one hand, it may be necessary to configure an -Xmx memory size that supports more JOSM plugins and other JOSM editing features. On the other hand, slow systems or those systems with few memory resources, can be stabilized by restricting JOSM memory use. These example Java memory settings provide examples that start with systems that have few memory resources to systems with vast amounts of memory.

-Xmx256m
-Xmx512m
-Xmx768m
-Xmx1024m
-Xmx1536m
-Xmx2048m

JOSM JVM options

provided as Java system properties

-Djosm.pref=/PATH/TO/JOSM/PREF            Set the preferences directory
-Djosm.userdata=/PATH/TO/JOSM/USERDATA    Set the user data directory
-Djosm.cache=/PATH/TO/JOSM/CACHE          Set the cache directory
-Djosm.home=/PATH/TO/JOSM/HOMEDIR         Relocate all 3 directories to homedir.
-Djosm.home=/path/to/JOSM/folder/         Change the folder for all user settings. Cache directory will be in homedir/cache

Note: -Djosm.home has lower precedence, i.e. the specific setting overrides the general one

Post jar options

These options need to be provided after the -jar josm.jar part of the command line.

--help|-h                                 Show this help
--geometry=widthxheight(+|-)x(+|-)y       Standard unix geometry argument
[--download=]minlat,minlon,maxlat,maxlon  Download the bounding box
[--download=]<URL>                        Download the location at the URL (with lat=x&lon=y&zoom=z)
[--download=]<filename>                   Open a file (any file type that can be opened with File/Open)
--downloadgps=minlat,minlon,maxlat,maxlon Download the bounding box as raw GPS
--downloadgps=<URL>                       Download the location at the URL (with lat=x&lon=y&zoom=z) as raw GPS
--selection=<searchstring>                Select with the given search

--[no-]maximize                           Launch in maximized mode
--reset-preferences                       Reset the preferences to default
--load-preferences=<url-to-xml>           Changes preferences according to the XML file
--set=<key>=<value>                       Set preference key to value
--language=<language>                     Set the language
--version                                 Displays the JOSM version and exits
--debug                                   Print debugging messages to console
--skip-plugins                            Skip loading plugins
--offline=<osm_api|josm_website|all>      Disable access to the given resource(s), separated by comma

examples

java -jar josm.jar track1.gpx track2.gpx london.osm
java -jar josm.jar https://www.openstreetmap.org/#map=13/43.2/11.1
java -jar josm.jar london.osm --selection=http://www.ostertag.name/osm/OSM_errors_node-duplicate.xml
java -jar josm.jar 43.2,11.1,43.4,11.4
java -jar josm.jar --set=expert=true
java -Djosm.pref=$XDG_CONFIG_HOME -Djosm.userdata=$XDG_DATA_HOME -Djosm.cache=$XDG_CACHE_HOME -jar josm.jar
java -Djosm.home=/home/user/.josm_dev -jar josm.jar
java -Xmx1024m -jar josm.jar

Parameters --download, --downloadgps and --selection are processed in this order. Make sure you load some data if you use --selection.

See also

• Preferences - overview page about all "preferences"
• jnlpOptions