Tomcat web.xml Dasel Query Patterns

<when_to_use>

Load this skill when querying a web.xml deployment descriptor — enumerating servlets, inspecting filter chains, listing listeners, extracting context parameters, or finding servlets by init-param value.

</when_to_use>

Domain skill for querying Tomcat web.xml files using dasel v3. Always use -i xml explicitly. XML attributes use - prefix in dasel friendly mode.

Servlet Discovery

# All servlet names
dasel -f web.xml -i xml 'web-app.servlet.map(servlet-name)'

# Count servlet definitions
dasel -f web.xml -i xml 'len(web-app.servlet)'

Filter Chain Analysis

# Find filters by class pattern (e.g., Security filters)
dasel -f web.xml -i xml 'web-app.filter.filter(filter-class ~ ".*Security.*")'

Replace Security with any class name fragment.

Listener Enumeration

# Count listener definitions
dasel -f web.xml -i xml 'len(web-app.listener)'

Context Parameters

# All context-param names
dasel -f web.xml -i xml 'web-app.context-param.map(param-name)'

Init Parameter Inspection

# Find servlets with a specific init-param name — filters parent collection by testing child length > 0
dasel -f web.xml -i xml 'web-app.servlet.filter(init-param.filter(param-name == "debug").len($this) > 0).map(servlet-name)'

Replace "debug" with the target param-name value.

All selectors require the full command prefix: dasel -f web.xml -i xml '<selector>'