NAME

dbcol - select columns from an Fsdb file

SYNOPSIS

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

DESCRIPTION

Select one or more columns from the input database. If a value is given for empty columns with the -e option, then any named columns which don't exist will be created. Otherwise, non-existent columns are an error.

Note: a safer way to create columns is dbcolcreate.

OPTIONS

-r or --relaxed-errors

Relaxed error checking: ignore columns that aren't there.

-v or --invert-match

Output all columns except those listed (like grep -v).

-e EmptyValue or --empty

Specify the value newly created columns get.

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 or Fsdb::BoundedQueue objects.

-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.

--header H

Use H as the full Fsdb header, rather than reading a header from then input.

--help

Show help.

--man

Show full manual.

SAMPLE USAGE

Input:

    #fsdb account passwd uid gid fullname homedir shell
    johnh * 2274 134 John_Heidemann /home/johnh /bin/bash
    greg * 2275 134 Greg_Johnson /home/greg /bin/bash
    root * 0 0 Root /root /bin/bash
    # this is a simple database

Command:

    cat DATA/passwd.fsdb account | dbcol account

Output:

    #fsdb      account
    johnh
    greg
    root
    # this is a simple database
    #  | dbcol account

SEE ALSO

dbcolcreate(1), Fsdb(3)

CLASS FUNCTIONS

new

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

Create a new dbcol 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: write trailer.

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.