1Fsdb::Filter::dbcol(3)User Contributed Perl DocumentationFsdb::Filter::dbcol(3)
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NAME

6       dbcol - select columns from an Fsdb file
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SYNOPSIS

9       dbcol [-v] [-e -] [column...]
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DESCRIPTION

12       Select one or more columns from the input database.  If a value is
13       given for empty columns with the -e option, then any named columns
14       which don't exist will be created.  Otherwise, non-existent columns are
15       an error.
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17       Note:  a safer way to create columns is dbcolcreate.
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OPTIONS

20       -r or --relaxed-errors
21           Relaxed error checking: ignore columns that aren't there.
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23       -v or --invert-match
24           Output all columns except those listed (like grep -v).
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26       -e EmptyValue or --empty
27           Specify the value newly created columns get.
28
29       and the standard fsdb options:
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31       -d  Enable debugging output.
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33       -i or --input InputSource
34           Read from InputSource, typically a file, or - for standard input,
35           or (if in Perl) a IO::Handle, Fsdb::IO or Fsdb::BoundedQueue
36           objects.
37
38       -o or --output OutputDestination
39           Write to OutputDestination, typically a file, or - for standard
40           output, or (if in Perl) a IO::Handle, Fsdb::IO or
41           Fsdb::BoundedQueue objects.
42
43       --autorun or --noautorun
44           By default, programs process automatically, but Fsdb::Filter
45           objects in Perl do not run until you invoke the run() method.  The
46           "--(no)autorun" option controls that behavior within Perl.
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48       --header H
49           Use H as the full Fsdb header, rather than reading a header from
50           then input.
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52       --help
53           Show help.
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55       --man
56           Show full manual.
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SAMPLE USAGE

59   Input:
60           #fsdb account passwd uid gid fullname homedir shell
61           johnh * 2274 134 John_Heidemann /home/johnh /bin/bash
62           greg * 2275 134 Greg_Johnson /home/greg /bin/bash
63           root * 0 0 Root /root /bin/bash
64           # this is a simple database
65
66   Command:
67           cat DATA/passwd.fsdb account | dbcol account
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69   Output:
70           #fsdb      account
71           johnh
72           greg
73           root
74           # this is a simple database
75           #  | dbcol account
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SEE ALSO

78       dbcolcreate(1), Fsdb(3)
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CLASS FUNCTIONS

81   new
82           $filter = new Fsdb::Filter::dbcol(@arguments);
83
84       Create a new dbcol object, taking command-line arguments.
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86   set_defaults
87           $filter->set_defaults();
88
89       Internal: set up defaults.
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91   parse_options
92           $filter->parse_options(@ARGV);
93
94       Internal: parse options
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96   setup
97           $filter->setup();
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99       Internal: setup, parse headers.
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101   run
102           $filter->run();
103
104       Internal: run over all data rows.
105
106   finish
107           $filter->finish();
108
109       Internal: write trailer.
110

112       Copyright (C) 1991-2018 by John Heidemann <johnh@isi.edu>
113
114       This program is distributed under terms of the GNU general public
115       license, version 2.  See the file COPYING with the distribution for
116       details.
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120perl v5.30.1                      2020-01-30            Fsdb::Filter::dbcol(3)
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