arthas/tutorials/katacoda/case-http-api-en/classpath-java-app.md

Get system properties of the Java application through Http api and extract the value of java.class.path.

json_data=$(curl -Ss -XPOST http://localhost:8563/api -d ' { "action":"exec", "command":"sysprop" }'){{execute T3}}

• Extract value with sed:

class_path=$(echo $json_data | tr -d '\n' | sed 's/.*"java.class.path":"\([^"]*\).*/\1/') echo "classpath: $class_path"{{execute T3}}

• Extract value with json_pp/awk:

class_path=$(echo $json_data | tr -d '\n' | json_pp | grep java.class.path | awk -F'"' '{ print $4 }') echo "classpath: $class_path"{{execute T3}}

Output:

classpath: arthas-demo.jar

NOTE:

• echo $json_data | tr -d '\n' : Delete line breaks (the value of line.separator) to avoid affecting the processing of sed/json_pp commands.
• awk -F'"' '{ print $4 }' : Use double quote as delimiter