Many messages you see are actually combined messages, often beginning with a program name. The five error messages in the following example are basically the same, even though the command names are different.
find: out of memory
grep: out of memory
ls: out of memory
mount: out of memory
fsck: out of memory
Rather than document this message at least five times, it appears in this book as the message "out of memory." Messages that contain colons (:) are often combined messages, and you might find that explanations of message sections are available separately.
If you don't find the beginning of a message in the book, and the message contains colons, search for other parts of the message.