# What does this line do?

**URL:** <https://get-help.theconstruct.ai/t/what-does-this-line-do/6729>\
**Category:** ROS Navigation In 5 Days\
**Created:** [December 7, 2020, 3:00am UTC](https://get-help.theconstruct.ai/t/what-does-this-line-do/6729 "2020-12-07T03:00:49Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![abdulbasitisdost](https://get-help.theconstruct.ai/user_avatar/get-help.theconstruct.ai/abdulbasitisdost/32/9348_2.png) [@abdulbasitisdost](https://get-help.theconstruct.ai/u/abdulbasitisdost)\
**Post date:** [December 7, 2020, 3:00am UTC](https://get-help.theconstruct.ai/t/what-does-this-line-do/6729/1 "2020-12-07T03:00:49Z")

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Professor, Below is the line from a launch file:  
`<rosparam file="$(find husky_navigation)/config/costmap_global_static.yaml" command="load" ns="global_costmap" unless="$(arg no_static_map)"/>`

1. What does rosparam do ?
2. What’s the function of **file** , **command** , **ns** , **unless** , and **if**?
3. Are the names in the 2nd question fixed ?

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**Author:** ![duckfrost2](https://get-help.theconstruct.ai/user_avatar/get-help.theconstruct.ai/duckfrost2/32/9365_2.png) [@duckfrost2](https://get-help.theconstruct.ai/u/duckfrost2)\
**Post date:** [December 7, 2020, 9:43am UTC](https://get-help.theconstruct.ai/t/what-does-this-line-do/6729/2 "2020-12-07T09:43:01Z")

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Hi ,

1. It loads all the parameters defined in that .yaml file into the ros parameter server, so that all the rosprogarms can access that data.

2. file: you define which file to load, command: tell this node what to do ( this is something unique of this rosparam tag ), ns: namespace of the data, in case you want to set those parameters inside a namespace . Very useful when various robots have the same names in the parameters.

3. Most of them, in this example yes, because the navigation system expects those values.

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**Author:** ![abdulbasitisdost](https://get-help.theconstruct.ai/user_avatar/get-help.theconstruct.ai/abdulbasitisdost/32/9348_2.png) [@abdulbasitisdost](https://get-help.theconstruct.ai/u/abdulbasitisdost)\
**Post date:** [December 7, 2020, 12:12pm UTC](https://get-help.theconstruct.ai/t/what-does-this-line-do/6729/3 "2020-12-07T12:12:07Z")

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What about **unless** and **if** , **Professor**  **Miguel** @duckfrost ?