1Fsdb::Filter::dbcol(3)User Contributed Perl DocumentationFsdb::Filter::dbcol(3)
2
3
4

NAME

6       dbcol - select columns from an Fsdb file
7

SYNOPSIS

9       dbcol [-v] [-e -] [column...]
10

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.
16
17       Note:  a safer way to create columns is dbcolcreate.
18

OPTIONS

20       -r or --relaxed-errors
21           Relaxed error checking: ignore columns that aren't there.
22
23       -v or --invert-match
24           Output all columns except those listed (like grep -v).
25
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.)
29
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).
35
36       and the standard fsdb options:
37
38       -d  Enable debugging output.
39
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.
44
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.
49
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.
54
55       --header H
56           Use H as the full Fsdb header, rather than reading a header from
57           then input.
58
59       --help
60           Show help.
61
62       --man
63           Show full manual.
64

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
72
73   Command:
74           cat DATA/passwd.fsdb account | dbcol account
75
76   Output:
77           #fsdb      account
78           johnh
79           greg
80           root
81           # this is a simple database
82           #  | dbcol account
83

SEE ALSO

85       dbcolcreate(1), Fsdb(3)
86

CLASS FUNCTIONS

88   new
89           $filter = new Fsdb::Filter::dbcol(@arguments);
90
91       Create a new dbcol object, taking command-line arguments.
92
93   set_defaults
94           $filter->set_defaults();
95
96       Internal: set up defaults.
97
98   parse_options
99           $filter->parse_options(@ARGV);
100
101       Internal: parse options
102
103   setup
104           $filter->setup();
105
106       Internal: setup, parse headers.
107
108   run
109           $filter->run();
110
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.
124
125
126
127perl v5.36.0                      2022-11-22            Fsdb::Filter::dbcol(3)
Impressum