CLI: --fetch causes exception

[mlep]

JabRef3.5 and JabRef-3.6dev--snapshot--2016-08-25--masterb73b236.jar
on Linux Mint.

Help file (although outdated --- I am in the process of updating it) states that the list of available fetchers can be printed out by typing in Jabref --fetch.

In fact, this causes an error message to be displayed (JabRef complains no option is given for this option), displays the help, and display another message.

Steps to reproduce:

• Launch Jabref --fetch

java -jar JabRef-3.6dev--snapshot--2016-08-25--master--b73b236.jar --fetch -n
11:49:27.552 [AWT-EventQueue-0] WARN  net.sf.jabref.cli.JabRefCLI - Problem parsing arguments
org.apache.commons.cli.MissingArgumentException: Missing argument for option: f
    at org.apache.commons.cli.DefaultParser.checkRequiredArgs(DefaultParser.java:211) ~[JabRef-3.6dev--snapshot--2016-08-25--master--b73b236.jar:?]
    at org.apache.commons.cli.DefaultParser.handleOption(DefaultParser.java:599) ~[JabRef-3.6dev--snapshot--2016-08-25--master--b73b236.jar:?]
    at org.apache.commons.cli.DefaultParser.handleShortAndLongOption(DefaultParser.java:480) ~[JabRef-3.6dev--snapshot--2016-08-25--master--b73b236.jar:?]
    at org.apache.commons.cli.DefaultParser.handleToken(DefaultParser.java:243) ~[JabRef-3.6dev--snapshot--2016-08-25--master--b73b236.jar:?]
    at org.apache.commons.cli.DefaultParser.parse(DefaultParser.java:120) ~[JabRef-3.6dev--snapshot--2016-08-25--master--b73b236.jar:?]
    at org.apache.commons.cli.DefaultParser.parse(DefaultParser.java:76) ~[JabRef-3.6dev--snapshot--2016-08-25--master--b73b236.jar:?]
    at org.apache.commons.cli.DefaultParser.parse(DefaultParser.java:60) ~[JabRef-3.6dev--snapshot--2016-08-25--master--b73b236.jar:?]
    at net.sf.jabref.cli.JabRefCLI.<init>(JabRefCLI.java:32) ~[JabRef-3.6dev--snapshot--2016-08-25--master--b73b236.jar:?]
    at net.sf.jabref.cli.ArgumentProcessor.<init>(ArgumentProcessor.java:73) ~[JabRef-3.6dev--snapshot--2016-08-25--master--b73b236.jar:?]
    at net.sf.jabref.JabRefMain.start(JabRefMain.java:109) ~[JabRef-3.6dev--snapshot--2016-08-25--master--b73b236.jar:?]
    at net.sf.jabref.JabRefMain.lambda$main$0(JabRefMain.java:41) ~[JabRef-3.6dev--snapshot--2016-08-25--master--b73b236.jar:?]
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311) [?:1.8.0_66]
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756) [?:1.8.0_66]
    at java.awt.EventQueue.access$500(EventQueue.java:97) [?:1.8.0_66]
    at java.awt.EventQueue$3.run(EventQueue.java:709) [?:1.8.0_66]
    at java.awt.EventQueue$3.run(EventQueue.java:703) [?:1.8.0_66]
    at java.security.AccessController.doPrivileged(Native Method) ~[?:1.8.0_66]
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76) [?:1.8.0_66]
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:726) [?:1.8.0_66]
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201) [?:1.8.0_66]
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116) [?:1.8.0_66]
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105) [?:1.8.0_66]
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) [?:1.8.0_66]
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93) [?:1.8.0_66]
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82) [?:1.8.0_66]
usage: jabref [OPTIONS] [BIBTEX_FILE]

Options: [-a <FILE>] [-asfl] [-b] [-d <FILE>] [--debug] [-f <FILE>] [-g]
       [-h] [-i <FILE>] [--importToOpen <FILE>] [-m <FILE>] [-n] [-o
       <FILE>] [-p <FILE>] [-v] [-x <FILE>]
 -a,--aux <FILE>                     Subdatabase from AUX:
                                     file[.aux],new[.bib]
 -asfl,--automaticallySetFileLinks   Automatically set file links
 -b,--blank                          Do not open any files at startup
 -d,--prdef <FILE>                   Reset preferences (key1,key2,... or
                                     'all')
    --debug                          Show debug level messages
 -f,--fetch <FILE>                   Run fetcher, e.g.
                                     "--fetch=Medline:cancer"
 -g,--generateBibtexKeys             Regenerate all keys for the entries
                                     in a BibTeX file
 -h,--help                           Display help on command line options
 -i,--import <FILE>                  Import file: filename[,import format]
    --importToOpen <FILE>            Import to open tab
 -m,--exportMatches <FILE>           [field]searchTerm,outputFile:
                                     file[,exportFormat]
 -n,--nogui                          No GUI. Only process command line
                                     options.
 -o,--output <FILE>                  Output or export file:
                                     filename[,export format]
 -p,--primp <FILE>                   Import preferences from file
 -v,--version                        Display version
 -x,--prexp <FILE>                   Export preferences to file

Available import formats:
  BibTeX         : bibtex
  BibTeXML       : bibtexml
  Biblioscape    : biblioscape
  Copac          : cpc
  INSPEC         : inspec
  ISI            : isi
  MSBib          : msbib
  Medline        : medline
  MedlinePlain   : medlineplain
  Ovid           : ovid
  PDFcontent     : pdfcontent
  REPEC New Economic Papers (NEP) : repecnep
  RIS            : ris
  Refer/Endnote  : refer
  SilverPlatter  : silverplatter
  XMP-annotated PDF : xmp
  text citations : textcitations

Available export formats: MSBib, ProdInraRIS, bibordf, bibtexml, din1505,
docbook, endnote, harvard, html, iso690rtf, iso690txt, listrefs, misq,
mods, ods, oocalc, oocsv, ris, simplehtml, tablerefs, tablerefsabsbib

Please report issues at https://github.com/JabRef/jabref/issues
Exception in thread "AWT-EventQueue-0" java.lang.RuntimeException
    at net.sf.jabref.cli.JabRefCLI.<init>(JabRefCLI.java:38)
    at net.sf.jabref.cli.ArgumentProcessor.<init>(ArgumentProcessor.java:73)
    at net.sf.jabref.JabRefMain.start(JabRefMain.java:109)
    at net.sf.jabref.JabRefMain.lambda$main$0(JabRefMain.java:41)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
    at java.awt.EventQueue.access$500(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:709)
    at java.awt.EventQueue$3.run(EventQueue.java:703)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

[koppor]

The updated help file is available at http://help.jabref.org/en/CommandLine

I think, it is currently not possible to list all fetchers, is it?

[lenhard]

Further discussion regarding the help and console messages for fetch will be tracked in #2016