When I try to start logstash using
/usr/share/logstash$ bin/logstash -e 'input{stdin{}}output{stdout{}}'
it gives
OpenJDK 64-Bit Server VM warning: Option UseConcMarkSweepGC was deprecated in version 9.0 and will likely be removed in a future release.
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.headius.backport9.modules.Modules (file:/usr/share/logstash/logstash-core/lib/jars/jruby-complete-9.2.9.0.jar) to method sun.nio.ch.NativeThread.signal(long)
WARNING: Please consider reporting this to the maintainers of com.headius.backport9.modules.Modules
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
WARNING: Could not find logstash.yml which is typically located in $LS_HOME/config or /etc/logstash. You can specify the path using --path.settings. Continuing using the defaults
Could not find log4j2 configuration at path /usr/share/logstash/config/log4j2.properties. Using default config which logs errors to the console
[FATAL] 2020-03-11 11:20:13.488 [main] runner - An unexpected error occurred! {:error=>#<ArgumentError: Path "/usr/share/logstash/data" must be a writable directory. It is not writable.>, :backtrace=>["/usr/share/logstash/logstash-core/lib/logstash/settings.rb:489:in validate'", "/usr/share/logstash/logstash-core/lib/logstash/settings.rb:271:in validate_value'", "/usr/share/logstash/logstash-core/lib/logstash/settings.rb:182:in block in validate_all'", "org/jruby/RubyHash.java:1428:in each'", "/usr/share/logstash/logstash-core/lib/logstash/settings.rb:181:in validate_all'", "/usr/share/logstash/logstash-core/lib/logstash/runner.rb:284:in execute'", "/usr/share/logstash/vendor/bundle/jruby/2.5.0/gems/clamp-0.6.5/lib/clamp/command.rb:67:in run'", "/usr/share/logstash/logstash-core/lib/logstash/runner.rb:242:in run'", "/usr/share/logstash/vendor/bundle/jruby/2.5.0/gems/clamp-0.6.5/lib/clamp/command.rb:132:in run'", "/usr/share/logstash/lib/bootstrap/environment.rb:73:in '"]}
[ERROR] 2020-03-11 11:20:13.516 [main] Logstash - java.lang.IllegalStateException: Logstash stopped processing because of an error: (SystemExit) exit