/ 
App-CSVUtils-1.034
River stage one • 3 direct dependents • 4 total dependents
/ csv-pick-fields

NAME

csv-pick-fields - Select one or more random fields from CSV

VERSION

This document describes version 1.034 of csv-pick-fields (from Perl distribution App-CSVUtils), released on 2024-02-02.

SYNOPSIS

csv-pick-fields --help (or -h, -?)

csv-pick-fields --version (or -v)

csv-pick-fields [--debug|--log-level=level|--quiet|--trace|--verbose] [--format=name|--json] [--inplace] [--inplace-backup-ext=str|-b=str] [--input-escape-char=str] [--input-header|--no-input-header|--noinput-header] [--input-quote-char=str] [--input-sep-char=str] [--input-tsv] [--(no)naked-res] [--num-fields=posint|-n=posint] [--output-always-quote|--no-output-always-quote|--nooutput-always-quote] [--output-escape-char=str] [--output-header|--no-output-header|--nooutput-header] [--output-quote-char=str] [--output-quote-empty|--no-output-quote-empty|--nooutput-quote-empty] [--output-sep-char=str] [--output-tsv|--no-output-tsv|--nooutput-tsv] [--overwrite|-O|--no-overwrite|--nooverwrite] [--page-result[=program]|--view-result[=program]] -- [input_filename] [output_filename]

See examples in the "EXAMPLES" section.

DESCRIPTION

OPTIONS

* marks required options.

Main options

--num-fields=s, -n

Number of fields to pick.

Default value:

1

Input options

--input-escape-char=s

Specify character to escape value in field in input CSV, will be passed to Text::CSV_XS.

Defaults to \\ (backslash). Overrides --input-tsv option.

--input-filename=s

Input CSV file.

Default value:

"-"

Use - to read from stdin.

Encoding of input file is assumed to be UTF-8.

Can also be specified as the 1st command-line argument.

--input-quote-char=s

Specify field quote character in input CSV, will be passed to Text::CSV_XS.

Defaults to " (double quote). Overrides --input-tsv option.

--input-sep-char=s

Specify field separator character in input CSV, will be passed to Text::CSV_XS.

Defaults to , (comma). Overrides --input-tsv option.

--input-tsv

Inform that input file is in TSV (tab-separated) format instead of CSV.

Overriden by --input-sep-char, --input-quote-char, --input-escape-char options. If one of those options is specified, then --input-tsv will be ignored.

--no-input-header

Specify that input CSV does not have a header row.

By default, the first row of the input CSV will be assumed to contain field names (and the second row contains the first data row). When you declare that input CSV does not have header row (--no-input-header), the first row of the CSV is assumed to contain the first data row. Fields will be named field1, field2, and so on.

Logging options

--debug

Shortcut for --log-level=debug.

--log-level=s

Set log level.

By default, these log levels are available (in order of increasing level of importance, from least important to most): trace, debug, info, warn/warning, error, fatal. By default, the level is usually set to warn, which means that log statements with level info and less important levels will not be shown. To increase verbosity, choose info, debug, or trace.

For more details on log level and logging, as well as how new logging levels can be defined or existing ones modified, see Log::ger.

--quiet

Shortcut for --log-level=error.

--trace

Shortcut for --log-level=trace.

--verbose

Shortcut for --log-level=info.

Output options

--format=s

Choose output format, e.g. json, text.

Default value:

undef

Output can be displayed in multiple formats, and a suitable default format is chosen depending on the application and/or whether output destination is interactive terminal (i.e. whether output is piped). This option specifically chooses an output format.

--inplace

Output to the same file as input.

Normally, you output to a different file than input. If you try to output to the same file (-o INPUT.csv -O) you will clobber the input file; thus the utility prevents you from doing it. However, with this --inplace option, you can output to the same file. Like perl's -i option, this will first output to a temporary file in the same directory as the input file then rename to the final file at the end. You cannot specify output file (-o) when using this option, but you can specify backup extension with -b option.

Some caveats:

  • if input file is a symbolic link, it will be replaced with a regular file;

  • renaming (implemented using rename()) can fail if input filename is too long;

  • value specified in -b is currently not checked for acceptable characters;

  • things can also fail if permissions are restrictive;

--inplace-backup-ext=s, -b

Extension to add for backup of input file.

Default value:

""

In inplace mode (--inplace), if this option is set to a non-empty string, will rename the input file using this extension as a backup. The old existing backup will be overwritten, if any.

--json

Set output format to json.

--naked-res

When outputing as JSON, strip result envelope.

Default value:

0

By default, when outputing as JSON, the full enveloped result is returned, e.g.:

[200,"OK",[1,2,3],{"func.extra"=>4}]

The reason is so you can get the status (1st element), status message (2nd element) as well as result metadata/extra result (4th element) instead of just the result (3rd element). However, sometimes you want just the result, e.g. when you want to pipe the result for more post-processing. In this case you can use --naked-res so you just get:

[1,2,3]
--output-always-quote

Whether to always quote values.

When set to false (the default), values are quoted only when necessary:

field1,field2,"field three contains comma (,)",field4

When set to true, then all values will be quoted:

"field1","field2","field three contains comma (,)","field4"
--output-escape-char=s

Specify character to escape value in field in output CSV, will be passed to Text::CSV_XS.

This is like --input-escape-char option but for output instead of input.

Defaults to \\ (backslash). Overrides --output-tsv option.

--output-filename=s, -o

Output filename.

Use - to output to stdout (the default if you don't specify this option).

Encoding of output file is assumed to be UTF-8.

Can also be specified as the 2nd command-line argument.

--output-header

Whether output CSV should have a header row.

By default, a header row will be output if input CSV has header row. Under --output-header, a header row will be output even if input CSV does not have header row (value will be something like "col0,col1,..."). Under --no-output-header, header row will not be printed even if input CSV has header row. So this option can be used to unconditionally add or remove header row.

--output-quote-char=s

Specify field quote character in output CSV, will be passed to Text::CSV_XS.

This is like --input-quote-char option but for output instead of input.

Defaults to " (double quote). Overrides --output-tsv option.

--output-quote-empty

Whether to quote empty values.

When set to false (the default), empty values are not quoted:

field1,field2,,field4

When set to true, then empty values will be quoted:

field1,field2,"",field4
--output-sep-char=s

Specify field separator character in output CSV, will be passed to Text::CSV_XS.

This is like --input-sep-char option but for output instead of input.

Defaults to , (comma). Overrides --output-tsv option.

--output-tsv

Inform that output file is TSV (tab-separated) format instead of CSV.

This is like --input-tsv option but for output instead of input.

Overriden by --output-sep-char, --output-quote-char, --output-escape-char options. If one of those options is specified, then --output-tsv will be ignored.

--overwrite, -O

Whether to override existing output file.

--page-result

Filter output through a pager.

This option will pipe the output to a specified pager program. If pager program is not specified, a suitable default e.g. less is chosen.

--view-result

View output using a viewer.

This option will first save the output to a temporary file, then open a viewer program to view the temporary file. If a viewer program is not chosen, a suitable default, e.g. the browser, is chosen.

Other options

--help, -h, -?

Display help message and exit.

--version, -v

Display program's version and exit.

COMPLETION

This script has shell tab completion capability with support for several shells.

bash

To activate bash completion for this script, put:

complete -C csv-pick-fields csv-pick-fields

in your bash startup (e.g. ~/.bashrc). Your next shell session will then recognize tab completion for the command. Or, you can also directly execute the line above in your shell to activate immediately.

It is recommended, however, that you install modules using cpanm-shcompgen which can activate shell completion for scripts immediately.

tcsh

To activate tcsh completion for this script, put:

complete csv-pick-fields 'p/*/`csv-pick-fields`/'

in your tcsh startup (e.g. ~/.tcshrc). Your next shell session will then recognize tab completion for the command. Or, you can also directly execute the line above in your shell to activate immediately.

It is also recommended to install shcompgen (see above).

other shells

For fish and zsh, install shcompgen as described above.

EXAMPLES

Pick 2 random fields row from CSV

% csv-pick-fields file.csv

HOMEPAGE

Please visit the project's homepage at https://metacpan.org/release/App-CSVUtils.

SOURCE

Source repository is at https://github.com/perlancar/perl-App-CSVUtils.

SEE ALSO

csv-pick-rows.

csv-pick-cells.

AUTHOR

perlancar <perlancar@cpan.org>

CONTRIBUTING

To contribute, you can send patches by email/via RT, or send pull requests on GitHub.

Most of the time, you don't need to build the distribution yourself. You can simply modify the code, then test via:

% prove -l

If you want to build the distribution (e.g. to try to install it locally on your system), you can install Dist::Zilla, Dist::Zilla::PluginBundle::Author::PERLANCAR, Pod::Weaver::PluginBundle::Author::PERLANCAR, and sometimes one or two other Dist::Zilla- and/or Pod::Weaver plugins. Any additional steps required beyond that are considered a bug and can be reported to me.

COPYRIGHT AND LICENSE

This software is copyright (c) 2024, 2023, 2022, 2021, 2020, 2019, 2018, 2017, 2016 by perlancar <perlancar@cpan.org>.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

BUGS

Please report any bugs or feature requests on the bugtracker website https://rt.cpan.org/Public/Dist/Display.html?Name=App-CSVUtils

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.