bufrextract.pl <bufr file(s)> [--ahl <ahl_regexp>] [--only_ahl] | [--without_ahl] [--outfile <filename>] [--reuse_ahl n] [--help] [--verbose n]
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.
--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.
--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).
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';
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.
Pål Sannes <firstname.lastname@example.org>
Copyright (C) 2010-2020 MET Norway