11
I have trouble understanding ls
's manual regarding a file that has rw-
mode. Here's the quote:
If
r
, the file is readable; if−
, it is not readable.If
w
, the file is writable; if−
, it is not writable.The first of the following that applies:
S
If in the owner permissions, the file is not executable and set-user-ID mode is set. If in the group permissions, the file is not executable and set-group-ID mode is set.
s
If in the owner permissions, the file is executable and set-user-ID mode is set. If in the group permissions, the file is executable and setgroup-ID mode is set.
x
The file is executable or the directory is searchable.
−
The file is neither readable, writable, executable, nor set-user-ID nor set-group-ID mode, nor sticky.
In particular, it seem that two sections in bold contradict each other: according to the first one, since the mode begins with r
, the file is readable, but according to the last one, the file is not readable. But, obviously, that is not the case.
So, what does that third section mean about file being "neither readable, writable..."?
Bibliography
- apple.com seems to be the source of the text quoted above. This is the man page (for OS X version 10.9, titled "BSD General Commands Manual"), and this is a discussion page that quotes it.
- ss64.com also has a copy of the OS X
ls
man page. - tuhs.org has the 4.4 BSD man page.
Beware: it uses
wwoorrdd
for bold and_w_o_r_d
for underline. - freebsd.org has the FreeBSD 10.1 man page, dated March 15, 2013.
- unix.com has a copy of the bad page under the man-page/freebsd directory (for FreeBSD 11.0). Note that they also have a copy of the correct page under man-page/posix.
- The "A+ 4 Real StudyExam4Less Computer Series"
contains the text quoted in the question,
plus a couple of paragraphs about
T
andt
, but not the entire man page. It is talking about OS X. You can see pages from two slightly different versions (editions?) of this book on books.google.com here and here. certiguide.com seems to be quoting them. - stevens.edu is a PDF file containing the BSD
(General Commands Manual) version of
ls(1)
. It is dated September 24, 2011.
Better:
- quora.com has the same text, but with the formatting (indentation) corrupted so badly that the meaning is ambiguous.
Better yet:
- cyberciti.biz and hurricanelabs.com have the same text, but with the indentation corrected to the point that one could argue that it's essentially OK. But they're both still really a mess.
Moved from here: http://stackoverflow.com/questions/31021900/what-does-third-symbol-in-rw-file-mode-mean
– Max Yankov – 2015-06-24T09:04:02.7071rwx -- read/write/execute – emirjonb – 2015-06-24T09:23:59.107
@emirjonb I'm not sure how this answers my question. – Max Yankov – 2015-06-24T09:24:38.350
Just a kindly remind, I dont know what are you going to achieve, but if you are just worrying permission problem, you can always
chomd 777
, which mean you have full control (read/write/execute) to the file/directory. – Bilo – 2015-06-24T09:26:55.647Please don't post the same question on multiple Stack Exchange sites simultaneously. ([SU] and [SO] are both Stack Exchange sites.) As it happens, this question belongs here and not on Stack Overflow. – Scott – 2015-06-24T09:29:00.790
You're not reading the second bold quote properly. That sentence begins with a minus sign (or hyphen), and is explaining what it means. – sawdust – 2015-06-24T09:29:25.150
2@sawdust According to this manual excerpt, a
rw-
file is simultaneously readable (r
), writable (w
) and neither readable nor writable (-
). – gronostaj – 2015-06-24T09:44:38.647Where is this "maunal excerpt" from? I cannot find this quoted text in the Linux man pages for
ls
. – sawdust – 2015-06-24T09:53:25.583@sawdust it's from OS X. – Max Yankov – 2015-06-24T10:24:29.243
@Bilo: Please do not tell people to do that. Not only is it (potentially) a massive security vulnerability, but it clobbers setuid/setgid/sticky bits, so
sudo chmod 777 $(which sudo)
will lock you out of the root account on systems that disable root login. – Kevin – 2015-06-24T16:04:06.337rw- means the file is readable, writable, but not executable. – CML – 2015-06-24T16:15:28.493
>
if there is a hyphen (-) it is a no – CML – 2015-06-24T16:16:48.600
1@CML I don't think that you read the question. – Max Yankov – 2015-06-24T17:05:47.763
Could you add a link with the source of this man page? ls elsewhere use a different wording. – Braiam – 2015-06-24T20:28:57.897
@Braiam: I added links to a few copies of the
ls
man page. – Scott – 2015-06-24T23:32:29.357