Logging Deleted Files

Command-line tools can be executed interactively by a user, but they’re often used as part of a larger script that coordinates several other tasks to automate a process. In both cases, it’s a good idea to provide constant feedback so the user or script knows that the tool is doing some work and it hasn’t hung unexpectedly.

Standard library

In general, we use STDOUT to provide feedback to the user onscreen. For scripts or tools that are executed in the background, such as a batch job, it’s useful to provide feedback in log files so the user can verify them later.

Go’s standard library provides the log package to facilitate logging information. By default, it will log information to STDERR, but we can configure it to log to a file instead. In addition to writing out the message, the logger automatically adds the date and time to each log entry. We can also configure it to add a prefix string to each entry, which helps improve searchability.

Let’s update the walk tool to log deleted files using this package.

Updating the imports

We begin by updating the imports section in the file actions.go, adding the log package:

Updating the delFile() function

We update the delFile() function so it accepts an additional argument called delLogger, which is a pointer to log.Logger. We use this logger in the body of the function to log information about the deleted file if the delete ...