I’ll go to the manual if I’m trying to understand how a particular thing works, or how to do a particular thing, but it’s not as useful to me for feature discovery.
From reading the sample of OP's book, it seems far more practical and accessible than the bash manual, so I'm not surprised that a lot of people would read OP's book that have no interest in reading the bash manual cover to cover.
> The diff utility can compare files and print their differences. If we pass it the result of ls commands, we can compare the contents of directories.
No, if you pass the output of ls commands, you might get an error because you'll pass a bunch of files to diff.
And last but not least there's
diff -r directory-a directory-b
to compare two directories file by file.I actually thought it was awesome to see that. I use this a lot to diff the output of commands and many people don't know about it.