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       -a or --all
27           Output all columns, in addition to those listed.  (Thus "-a foo"
28           will move column foo to the first column.)
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30       -e EmptyValue or --empty
31           Specify the value newly created columns get.
32
33       --saveoutput $OUT_REF
34           Save output writer (for integration with other fsdb filters).
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36       and the standard fsdb options:
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38       -d  Enable debugging output.
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40       -i or --input InputSource
41           Read from InputSource, typically a file, or - for standard input,
42           or (if in Perl) a IO::Handle, Fsdb::IO or Fsdb::BoundedQueue
43           objects.
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45       -o or --output OutputDestination
46           Write to OutputDestination, typically a file, or - for standard
47           output, or (if in Perl) a IO::Handle, Fsdb::IO or
48           Fsdb::BoundedQueue objects.
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50       --autorun or --noautorun
51           By default, programs process automatically, but Fsdb::Filter
52           objects in Perl do not run until you invoke the run() method.  The
53           "--(no)autorun" option controls that behavior within Perl.
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55       --header H
56           Use H as the full Fsdb header, rather than reading a header from
57           then input.
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59       --help
60           Show help.
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62       --man
63           Show full manual.
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SAMPLE USAGE

66   Input:
67           #fsdb account passwd uid gid fullname homedir shell
68           johnh * 2274 134 John_Heidemann /home/johnh /bin/bash
69           greg * 2275 134 Greg_Johnson /home/greg /bin/bash
70           root * 0 0 Root /root /bin/bash
71           # this is a simple database
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73   Command:
74           cat DATA/passwd.fsdb account | dbcol account
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76   Output:
77           #fsdb      account
78           johnh
79           greg
80           root
81           # this is a simple database
82           #  | dbcol account
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SEE ALSO

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

88   new
89           $filter = new Fsdb::Filter::dbcol(@arguments);
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91       Create a new dbcol object, taking command-line arguments.
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93   set_defaults
94           $filter->set_defaults();
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96       Internal: set up defaults.
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98   parse_options
99           $filter->parse_options(@ARGV);
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101       Internal: parse options
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103   setup
104           $filter->setup();
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106       Internal: setup, parse headers.
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108   run
109           $filter->run();
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111       Internal: run over all data rows.
112
113   finish
114           $filter->finish();
115
116       Internal: write trailer.
117

119       Copyright (C) 1991-2022 by John Heidemann <johnh@isi.edu>
120
121       This program is distributed under terms of the GNU general public
122       license, version 2.  See the file COPYING with the distribution for
123       details.
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127perl v5.36.0                      2023-01-20            Fsdb::Filter::dbcol(3)
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