Calculate the sha256sum for a single file.

This is an action to calculate the sha256sum for a specific file. This is particularly useful for verifying ISOs for example.

This is a different action from verify-sha256sum@rcalixte that prompts for the sha256sum hash before proceeding further. This will only display the sha256sum hash in a dialog where it can be copied.

The following programs must be installed and available:

• gettext for translations in the action's script
• sha256sum to calculate the hash of file
• zenity to display the dialog with the result