When you open a library, EagleFiler checks that all the files and notes are present. The Verify command does this, and it additionally checks that their contents are what EagleFiler was expecting.
This can help you detect file corruption before it becomes a serious problem. For example, if there is damage to your disk and a file becomes corrupt, you’ll learn of the problem as soon as you use the Verify command. Without Verify, you would only learn of the problem when you tried to access the file (perhaps a long time in the future), and perhaps not even then, because the corruption might not be readily apparent. Because you learn about the damage early, you can restore a correct version of the file from a backup, rather than filling your future backups with damaged copies of the file.
In order to detect when files have changed, EagleFiler stores a checksum of each file. If EagleFiler reads a file and calculates the same checksum that it got before, it knows that the file has not changed. Thus, if the file was in good condition before, it is still in good condition. If EagleFiler calculates a different checksum, that means that the file’s contents are different.
Sometimes, the checksum should be different. For example, when you edit a file, you intentionally change its contents, resulting in a different checksum. When you edit a file within EagleFiler, EagleFiler automatically updates its stored checksum to match the file’s new contents. Thus, if you only edit files using EagleFiler, the checksums will always be in sync with the files’ contents, and any checksum that doesn’t match means that the file is damaged.
EagleFiler also allows you edit files using other applications. For example, you can double-click a Microsoft Word document to open it in Word, make some changes, and choose File ‣ Save. In this case, the file has changed, but there is no way for EagleFiler to know that this is because of what you did in Word. The changes could have been due to damage. Thus, if you edit a file outside of EagleFiler, you must use the Update Checksum to tell EagleFiler that the file’s current contents are correct. EagleFiler will then update its stored checksum to match.
Verify is a specialized feature for people who want extra data integrity protection. If you don’t need this, or if you frequently edit files outside of EagleFiler and don’t want to have to Update Checksum, then you can simply ignore the Verify command. EagleFiler will then behave like a normal Mac application: it won’t complain about files being different than it expected, but neither will it detect when they are damaged.