Depreacte --output-format, only allow --output option

[Sea-n]

Current situation

• The help message says "-o --output=file.html|json|csv - Output either an HTML, JSON or a CSV file."
• While using -o (and the deprecated --output-format), it will trigger read_option_args: case 'o'
  • This one checks valid_output_type first, then stores it to output_formats.
• When using --output, it will trigger parse_long_opt: "output"
  • This one stores it to output_formats directly.

The bug I encountered

While using --output out.tsv, it runs through the parsing process and has no output file.
When changed to -o out.tsv for short, it finally gives me the "invalid filename extension" error.

Refer to commit history

• In 2016 Jun 2e7c4b8, Added an --output=file.[html|csv|json] as a shortcut to --output-format
• In 2017 Apr 91da175, Updated README.md with Docker details
  • Changed output-format to output in README.
• In 2017 Jun 6309ed6, Fix error in example config file
  • The latest --output-format in this repo (except src/options.c) is removed.
• In 2017 Oct 27d8782, Add valid_output_type() to validate the filename given via -o
  • The file extension check is only applied for -o (--output-format), and the PR author forgot about --output.

According to the commit history, we can see that --output-format has been replaced for 6+ years. I think it's safe to remove it without any warning.

So after this PR is merged, --output-format will only output a fatal error, saying it's deprecated, without backward compatibility.

[Sea-n]

Update:
Now I know -o file.csv will save the output to a file, while -o csv will directly display it in the terminal.
It's currently not included in the help message. 😅

I need your assistance in improving the proposed wording, thanks. 🙇‍♂️

[allinurl]

I believe we can include a third line to show both options, and a brief example, like the one you posted above, would suffice. Thanks!

[Sea-n]

I still not confident about how to write the text with short word.

Here is some version (with inspiration of ChatGPT), which one would you preferred?

(A)
-o --output=<format|filename>   - Output to stdout or the specificed file.
                                  Currently support HTML, JSON and CSV format.
                                                                               *
(B)                                                                            *
-o --output=<format|filename>   - Specify the output format or output filename.
                                  The filename must have .html, .json, or .csv extension.
                                                                               *
(C)                                                                            *
-o --output=<html|json|csv>     - Specify the output format.
-o --output=<FILENAME>          - Save report to a file. The FILENAME must
                                  have .html, .json, or .csv extension.
                                                                               *
(D)                                                                            *
-o --output=[FILE.]<FORMAT>     - Output to stdout or the specificed file.
                                  Supported FORMAT: html, json, csv.
                                                                               *
(E)                                                                            *
-o --output=<html|json|csv|FILE> - Set output format or write to a file.
                                   The FILE must have .html, .json, or .csv extension.
                                                                               *
(F)                                                                            *
-o --output=[file.]<html|json|csv> - Output to stdout or the specificed file.

                                                                               *
(G)                                                                            *
-o --output=<format|filename>   - Output to stdout or the specificed file.
                                  e.g., --output=report.html, -o out.json, --output=csv
                                                                               *
  (Current longest text)                                                       *
--unknowns-as-crawlers          - Classify unknown OS and browsers as crawlers.
--external-assets               - Output HTML assets to external JS/CSS files.

[allinurl]

Thanks for posting these options. Let's roll with G; I think that's pretty clear, in my opinion.

[Sea-n]

Okay! Just pushed a new version. ☺️

And I do a little adjustment here, think it would be more readable.

(From this)
-o --output=<format|filename>   - Output to stdout or the specified file.
                                  e.g., --output=report.html, -o out.json, --output=csv

(Changed to this)
-o --output=<format|filename>   - Output to stdout or the specified file.
                                  e.g., -o csv, -o out.json, --output=report.html

[allinurl]

Thanks, Sean! The changes have been merged.