[
http://issues.apache.org/jira/browse/NUTCH-143?page=comments#action_12360689 ]
Matt Kangas commented on NUTCH-143:
-----------------------------------
I'd like to see this fixed too. It would make error-checking in wrapper scripts
much simpler to implement.
A fix would have to touch every .java file that has a main() method, because
the problem is that the JVM returns status=0 from main(), because main() has a
_void_ return type, after all.
To solve this, I recommend renaming all existing "main()" methods to "doMain()"
and adding the following to each affected file:
/**
* main() wrapper that returns proper exit status
*/
public static void main(String[] args) {
Runtime rt = Runtime.getRuntime();
try {
boolean status = doMain(args);
rt.exit(status ? 0 : 1);
}
catch (Exception e) {
LOG.log(Level.SEVERE, LOGPREFIX + "error, caught Exception in main()",
e);
rt.exit(1);
}
}
> Improper error numbers returned on exit
> ---------------------------------------
>
> Key: NUTCH-143
> URL: http://issues.apache.org/jira/browse/NUTCH-143
> Project: Nutch
> Type: Bug
> Versions: 0.8-dev
> Reporter: Rod Taylor
>
> Nutch does not obey standard command line error numbers which can make it
> difficult to script around commands.
> Both of the below should have exited with an error number larger than 0
> causing the shell script to enter into the 'Failed' case.
> bash-3.00$ /opt/nutch/bin/nutch updatedb && echo "==>Success" || echo
> "==>Failed"
> Usage: <crawldb> <segment>
> ==>Success
> bash-3.00$ /opt/nutch/bin/nutch readdb && echo "==>Success" || echo
> "==>Failed"
> Usage: CrawlDbReader <crawldb> (-stats | -dump <out_dir> | -url <url>)
> <crawldb> directory name where crawldb is located
> -stats print overall statistics to System.out
> -dump <out_dir> dump the whole db to a text file in <out_dir>
> -url <url> print information on <url> to System.out
> ==>Success
> Note that the nutch shell script functions as expected:
> bash-3.00$ /opt/nutch/bin/nutch && echo "==>Success" || echo "==>Failed"
> Usage: nutch COMMAND
> where COMMAND is one of:
> crawl one-step crawler for intranets
> readdb read / dump crawl db
> readlinkdb read / dump link db
> admin database administration, including creation
> inject inject new urls into the database
> generate generate new segments to fetch
> fetch fetch a segment's pages
> parse parse a segment's pages
> updatedb update crawl db from segments after fetching
> invertlinks create a linkdb from parsed segments
> index run the indexer on parsed segments and linkdb
> merge merge several segment indexes
> dedup remove duplicates from a set of segment indexes
> server run a search server
> namenode run the NDFS namenode
> datanode run an NDFS datanode
> ndfs run an NDFS admin client
> jobtracker run the MapReduce job Tracker node
> tasktracker run a MapReduce task Tracker node
> job manipulate MapReduce jobs
> or
> CLASSNAME run the class named CLASSNAME
> Most commands print help when invoked w/o parameters.
> ==>Failed
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