Originally Posted by
him610
+1. Good book with topics covered IN THE CORRECT ORDER. Learning things in the correct order means you'll have the background as skills build on previously learned skills and understanding. Otherwise, the connections won't be made and things will seem thrown together and much harder to learn. But with the connections, in the proper order, the pieces will fit and things will connect, so the puzzle gets filled in with each new topic and the different aspects of early topics make more and more and more sense. There is an elegance to Unix. As understanding becomes deeper, you'll be able to do things that nobody taught, but because you understand how things work internally, that the new idea you have will work.
Stamp out cat abuse!!!
Don't do this:
Code:
sudo cat boot.log|less
Why not?
- cat isn't needed. Using it is wasteful.
- the file specified assumes it is in the current directory - it is not. Actually, my 18.04 system doesn't have a file named "boot.log" at all.
- use less /var/log/bootstrap.log
- bootstrap.log doesn't need sudo to read.
On 20.04, and perhaps later releases, there is a /var/log/boot.log ... that appears to be rotated and compressed at boot.
Code:
$ ll /var/log/boot.log*
-rw------- 1 root root 7521 Oct 10 11:44 /var/log/boot.log
-rw------- 1 root root 7614 Oct 3 00:00 /var/log/boot.log.1
-rw------- 1 root root 7824 Sep 28 00:00 /var/log/boot.log.2
-rw------- 1 root root 7889 Sep 19 00:00 /var/log/boot.log.3
-rw------- 1 root root 7922 Sep 12 00:00 /var/log/boot.log.4
-rw------- 1 root root 15692 Sep 9 00:00 /var/log/boot.log.5
-rw------- 1 root root 7235 Aug 30 00:00 /var/log/boot.log.6
-rw------- 1 root root 7472 Aug 22 00:00 /var/log/boot.log.7
That output tells me that sudo is necessary.
sudo less /var/log/boot.log
is the command to use. Whenever someone types cat, they are probably wasting 2 extra, unneeded, processes. It is wasteful and unnecessary. Nearly all of the programs like less, more, grep, and 99.99999999999999999% of the others accept a filename as input.
less is what we call a PAGER. more is another. By setting an environment variable, PAGER=less, you'll have less used by all programs that want to show stuff a page at a time. I generally prefer less over more, because it allows going backwards in the buffer, not just forwards. There's 1 thing I dislike about less (the default settings) and that is that it clears the screen when it is done. More leaves the screen content alone. There are times when both modes are useful.
Stamp out cat abuse!!!
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