Bug#886173: general: ls quotes results with special characters in its output

[mqudsi@neosmart.net]

Package: general
Severity: normal

Dear Maintainer,

On a clean installation of debian buster, I ran into an issue where the
output of `ls` in various modes led me to confusedly attempt to figure
out where my scripting had gone wrong.

In particular, `ls` output (both in regular and `-l` modes) wraps in
single quotes the names of files that contain special characters (or, at
least, a parenthesis), meaning its output is not an accurate reflection
of the actual contents of the directory.

Observe:

```
mqudsi@buster ~> touch test\(
mqudsi@buster ~> ls -l
mqudsi@buster ld ~> ls -l
-rw-r--r-- 1 mqudsi mqudsi         0 Jan  2 14:22 'test('
```

In my case, I had downloaded a file via `wget` that contained a
parenthesis in its filename. After running `ls`, I presumed that there
was a bug in my shell that passed in the parentheses to `wget`, as I
presumed that `ls` was showing me what was actually there.

Additionally, the output cannot be copied-and-pasted as it is. What is
the point of injecting quotes if they don't actually escape/quote their
content? To illustrate with an example:

```
mqudsi@buster ~> touch \$\(test\)
mqudsi@buster ~> ls -l
-rw-r--r-- 1 mqudsi mqudsi    0 Jan  2 14:27 '$(test)'
```

That's not shell-safe, but the quotes might lead you to think it were.

Moreover, the quoting behavior is... weird. I'm not sure what is meant
to be quoted below -- actually, after seeing the output of ls, I'm no
longer sure of anything and have no clue what actually exists on my
filesystem and what doesn't:

```
mqudsi@buster ~> touch \'\test\(\'
mqudsi@buster ~> ls -l
-rw-r--r-- 1 mqudsi mqudsi    0 Jan  2 14:22 ''\''test('\'''
```

I think we can all agree that's a bit confusing?

(I'm not clear on whether this is simply a bug or by design, so I'm
hedging my bets and pointing out why it's not a good idea just in case
this behavior was intentional.)

There's no good way to account for all inputs or to account for the
idiosyncrasies of the quoting behavior of all the different shells. It's
not `ls`'s job to insulate the user from making quotes mistakes when
referencing files, if only because in attempting to do so it makes
things a lot worse:

```
mqudsi@buster ~> ls -l
-rw-r--r-- 1 mqudsi mqudsi    0 Jan  2 14:27 '$(test)'
mqudsi@buster ~> rm '$(test)' #copy-and-pasted unsafely w/ side-effects
# operation fails, with potentially dangerous side effects
mqudsi@buster ~> rm \'\$(test\)\' #presuming ls output is not quoted
# operation fails because file does not exist
mqudsi@buster ~> rm test\(
# all it took to doing it right
```

Hopefully this behavior can be changed to simply listing the contents of
the specified directory as-is.

Thank you,

Mahmoud Al-Qudsi
NeoSmart Technologies

-- System Information:
Debian Release: buster/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 4.13.0-1-amd64 (SMP w/1 CPU core)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)