[ale] find + ls commands: commentary [was: Bash script]

[Ron]

I'm self-replying because, instead of getting all defensive, I'm gonna
share an explanation on what is going on with `find` so anyone still
reading this thread can benefit.


I chose `find` because it traverses directories by default, and this can
be controlled with the -maxdepth and -mindepth options.


One can have find execute a command on the found items via the -exec option.


It gets a bit tricky if one wants to pipe that output to somewhere else,
as `find` wants to send everything after the -exec to the specified
program... until it encounters a ";", which needs to be escaped as "\;".

However, that will invoke the -exec program once for each found item.

If one were to use "\+" instead, `find` will bundle up all the found
results and pass them along at once.


This is perfect for our `ls` command: it can take everything found
anywhere on the SSD and sort it internally, which it's built for and
there's no gotcha on file sizes, etc.


There is a wee gotcha with `ls` though.

If including directories in the `find` search, and then we run `ls` on
them, their *contents* will be listed, along with "total: ###", blank
lines, etc.

So, -d or --directory will "list directories themselves, not their
contents".


Finally, we pipe through `tail` (not `head` since we'll get that "signal
13" error) and trim to the number of lines needed.

Should be one line, but it depends on whether `ls -a` or `ls -A` (--all
or --almost-all) are used, where the `find` is run in relation to the
searched directories, and other things I can't think of.


Hopefully someone benefits from this and I haven't made too many errors
in writing it up.



Here's some tests one can play with to see what's going on:

find /tmp -exec ls -dltrA {} \+  | less


Notice that /tmp itself is the newest entry which may or may not be desired.