SYNOPSIS

  bufrextract.pl <bufr file(s)>
      [--ahl <ahl_regexp>]
      [--only_ahl] | [--without_ahl]
      [--outfile <filename>]
      [--reuse_ahl n]
      [--help]
      [--verbose n]

DESCRIPTION

Extract all BUFR messages and/or corresponding AHLs from BUFR file(s), possibly filtering on AHL.

The AHL (Abbreviated Header Line) is recognized as the TTAAii CCCC DTG [BBB] immediately preceding the BUFR message.

Execute without arguments for Usage, with option "--help" for some additional info. See also <https://wiki.met.no/bufr.pm/start> for examples of use.

OPTIONS

   --ahl <ahl_regexp> Extract BUFR messages and/or AHLs with AHL
                      matching <ahl_regexp> only
   --only_ahl         Extract AHLs only
   --without_ahl      Extract BUFR messages only
   --outfile <filename>
                      Will print to <filename> instead of STDOUT
   --reuse_ahl n  n=0 (default) AHL is considered belonging to a BUFR message
                      only if immediately preceding
                  n=1 When filtering using --ahl: Reuse last AHL found if current
                      BUFR message has no immediately preceding AHL
   --help             Display Usage and explain the options used. For even
                      more info you might prefer to consult perldoc bufrextract.pl
   --verbose n        Set verbose level to n, 0<=n<=6 (default 0)

Options may be abbreviated, e.g. "--h" or "-h" for "--help".

For option "--ahl" the <ahl_regexp> should be a Perl regular expression. E.g. "--ahl 'ISS... ENMI'" will decode only BUFR SHIP (ISS) from CCCC=ENMI.

If the BUFR file(s) are known to consist solely of GTS bulletins, you might consider setting "--reuse 1" when applying "--ahl", in order to extract all (and not only the first) BUFR messages in multi message bulletins. Such bulletins are very rare nowadays, however, and see also the "CAVEAT" for more on this option. Note that the corresponding AHL is still extracted (and printed) only once.

No bufrtables are needed for running bufrextract.pl, since section 4 in BUFR message will not be decoded (which also speeds up execution quite a bit).

HINTS

With a little knowledge of Perl you could easily extend bufrextract.pl to extract BUFR messages based on whatever information is available in section 0-3, by making your own copy of bufrextract.pl and then employing one of the many "get_" subroutines in BUFR.pm. For example, to extract only BUFR messages with data category 1, add the following line just before calling "is_filtered()" in code:

  next if $bufr->get_data_category() != 1;

Or to extract BUFR messages with TM315009 only:

  next if bufr->get_descriptors_unexpanded() ne '315009';

CAVEAT

Sometimes GTS bulletins are erroneously issued with extra characters between the GTS AHL and the start of BUFR message (besides the standard character sequence CRCRLF), likely leading bufrextract.pl to miss the AHL. Also, if applying "--reuse 1", the BUFR message of such a GTS bulletin will then be wrongly associated with the AHL of the previous GTS bulletin when filtering on AHL. If bulletins with this kind of error is more of a concern than multi message bulletins, you should probably refrain from making use of the "--reuse 1" option.

AUTHOR