Скачать или смотреть How to Log wkhtmltopdf Command Output to a File on Windows

Discover how to effectively log the output of the `wkhtmltopdf` command in Windows to a file, avoiding blank lines.
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How to Log wkhtmltopdf Command Output to a File on Windows

If you've ever tried logging the output of the wkhtmltopdf command on Windows, you may have been frustrated to find that the output file was filled with nothing but blank lines. This problem can be especially bewildering, considering that the command works perfectly in the Command Prompt (CMD) without any visible issues. In this guide, we'll explore a straightforward solution to this issue, ensuring that your logging hits the mark.

The Problem: Blank Log Files

You might encounter a situation where running the following command in CMD:

[[See Video to Reveal this Text or Code Snippet]]

results in a log file (C:\test.txt) that is entirely blank or contains just blank lines. However, when you execute the command directly in CMD, you see proper documentation and output, such as:

[[See Video to Reveal this Text or Code Snippet]]

So, how do we capture this output accurately in a log file? Let’s delve into the solution.

The Solution: Correct Command Syntax

The good news is that there is a relatively simple adjustment to the command syntax that can resolve this output logging issue. Instead of just redirecting standard output, you will need to also account for the standard error output. This is where our revised command comes into play.

Revised Command

Here’s the new command structure that worked effectively:

[[See Video to Reveal this Text or Code Snippet]]

Breakdown of the Command

C:\PROGRA~1\wkhtmltopdf\bin\wkhtmltopdf: This is the path to the wkhtmltopdf executable file.

1 C:\test.txt: This part redirects standard output (1) to the specified file (C:\test.txt). The double greater-than symbol (>>) appends the output rather than overwriting it.

2 &1: This notation combines standard error output (2) with standard output (1). By doing this, any errors produced will also be captured in the same log file.

Why Does This Work?

In Windows, commands might produce output in two different streams:

Standard Output (stdout): Regular output, typically what the program is designed to send to the terminal.

Standard Error (stderr): Error messages or warnings that the program generates.

By using 2>&1, you ensure you're capturing both stdout and stderr into your log file, which prevents the scenario of having no information logged due to errors not being captured.

Conclusion

Logging the output of the wkhtmltopdf command in Windows doesn’t have to be a headache. With the correct command format, you can easily redirect all outputs – including error messages – to your desired log file. Remembering to specify both standard output and error output will not only save you from the hassle of blank log files, but it will also provide you with comprehensive logs that can help diagnose potential issues in the future.

If you have any other questions or further issues regarding command line tools, feel free to reach out, and we’ll be happy to help!