Fsdb::Filter::dbsubprocess(3)

NAME
dbsubprocess - invoke a subprocess as a Fsdb filter object

SYNOPSIS
    dbsubprocess [--] program [arguments...]

DESCRIPTION
Run PROGRAM as a process, with optional ARGUMENTS as program arguments, feeding its standard input and standard output as fsdb streams. A "--" can separate arguments to dbsubprocess from the program and its arguments.

As with similar tools, like open2, the caller is expected to take care that the subprocess does not deadlock.

This program is primarily for internal use by dbmapreduce.

Like dbpipeline, dbsubprocess program does have a Unix command; instead it is used only from within Perl.

OPTIONS

-w or --warnings
    Enable warnings in user supplied code. (Default to include warnings.)

-E or --endsub SUB
    Call Perl SUB when the subprocess terminates. The sub runs in the parent and is a Fred ending sub, see Fsdb::Support::Freds.

and the standard fsdb options:

-d  Enable debugging output.

-i or --input InputSource
    Read from InputSource, typically a file, or - for standard input, or (if in Perl) a IO::Handle, Fsdb::IO objects. (For this case, it cannot be Fsdb::BoundedQueue).

-o or --output OutputDestination
    Write to OutputDestination, typically a file, or - for standard output, or (if in Perl) a IO::Handle, Fsdb::IO or Fsdb::BoundedQueue objects.

--autorun or --noautorun
    By default, programs process automatically, but Fsdb::Filter objects in Perl do not run until you invoke the run() method. The "--(no)autorun" option controls that behavior within Perl.

--help
    Show help.

--man
    Show full manual.

SAMPLE USAGE

  Input:
        #fsdb name id test1
        a       1       80
        b       2       70
        c       3       65
        d       4       90
        e       5       70
        f       6       90

  Command:
the following perl code:

    use Fsdb::Filter::dbsubprocess;
    my $f = new Fsdb::Filter::dbsubprocess(qw(cat));
    $f->setup_run_finish;
    exit 0;

  Output:
        #fsdb name id test1
        a       1       80
        b       2       70
        c       3       65
        d       4       90
        e       5       70
        f       6       90
        #   | dbsubprocess cat

SEE ALSO
dbpipeline(1), Fsdb(3)

CLASS FUNCTIONS

  new
    $filter = new Fsdb::Filter::dbsubprocess(@arguments);

Create a new dbsubprocess object, taking command-line arguments.

  set_defaults
    $filter->set_defaults();

Internal: set up defaults.

  parse_options
    $filter->parse_options(@ARGV);

Internal: parse options

  setup
    $filter->setup();

Internal: setup, parse headers.

  run
    $filter->run();

Internal: run over all data rows.

  finish
    $filter->finish();

Internal: run over all data rows.

AUTHOR and COPYRIGHT
Copyright (C) 1991-2018 by John Heidemann <johnh@isi.edu>

This program is distributed under terms of the GNU general public license, version 2. See the file COPYING with the distribution for details.