Like einfo, we output a helpful message and then hint that the following operation may take some time to complete. Once the task is finished, you need to call eend.
Followup the ebegin message with an appropriate "OK" or "!!" (for errors) marker. If status is non-zero, then the additional error message is displayed.
Same as elog, but should be used when the message isn't important to the user (like progress or status messages during the build process).
If you need to display a message that you wish the user to read and take notice of, then use elog. It works just like echo(1), but adds a little more to the output so as to catch the user's eye. The message will also be logged by portage for later review.