I know what it means for a file to have suid permission. It means when other users have execute permission for it, they execute as the owner of the file. But what does it imply when a folder has suid permission? I did some testing and it seems nothing special for the folder. Could anyone help to plain a little? Thanks.  I'm using Oracle Linux 7.6.  root:[~]# cat /etc/*release* Oracle Linux Server release 7.6 NAME="Oracle Linux Server" VERSION="7.6" ID="ol" VARIANT="Server" VARIANT_ID="server" VERSION_ID="7.6" PRETTY_NAME="Oracle Linux Server 7.6" ANSI_COLOR="0;31" CPE_NAME="cpe:/o:oracle:linux:7:6:server" HOME_URL="https://linux.oracle.com/" BUG_REPORT_URL="https://bugzilla.oracle.com/"  ORACLE_BUGZILLA_PRODUCT="Oracle Linux 7" ORACLE_BUGZILLA_PRODUCT_VERSION=7.6 ORACLE_SUPPORT_PRODUCT="Oracle Linux" ORACLE_SUPPORT_PRODUCT_VERSION=7.6 Red Hat Enterprise Linux Server release 7.6 (Maipo) Oracle Linux Server release 7.6 cpe:/o:oracle:linux:7:6:server root:[~]#   Below is my testing on a freshly installed server.  root:[~]# pwd /root root:[~]# ls -lad /root dr-xr-x---. 9 root root 4096 Aug 16 22:07 /root root:[~]# mkdir test root:[~]# ls -lad test drwxr-xr-x. 2 root root 4096 Aug 16 22:07 test root:[~]# root:[~]# useradd a root:[~]# passwd a Changing password for user a. New password: BAD PASSWORD: The password is a palindrome Retype new password: passwd: all authentication tokens updated successfully. root:[~]# chmod u+s test root:[~]# root:[~]# su - a [a@localhost ~]$ cd /root/test -bash: cd: /root/test: Permission denied [a@localhost ~]$ cd /root -bash: cd: /root: Permission denied [a@localhost ~]$ logout root:[~]# root:[~]# ls -lad /root dr-xr-x---. 10 root root 4096 Aug 16 22:07 /root root:[~]# chmod o+x /root root:[~]# root:[~]# su - a Last login: Fri Aug 16 22:08:54 CST 2019 on pts/0 [a@localhost ~]$ cd /root/test [a@localhost test]$ [a@localhost test]$ pwd /root/test [a@localhost test]$ ls -la . total 8 drwsr-xr-x.  2 root root 4096 Aug 16 22:07 . dr-xr-x--x. 10 root root 4096 Aug 16 22:07 .. [a@localhost test]$ touch file1 touch: cannot touch ‘file1’: Permission denied [a@localhost test]$ logout root:[~]# root:[~]# chmod o+w test/ root:[~]# root:[~]# su - a Last login: Fri Aug 16 22:09:31 CST 2019 on pts/0 [a@localhost ~]$ [a@localhost ~]$ cd /root/test [a@localhost test]$ touch file1 [a@localhost test]$ ls -la total 8 drwsr-xrwx.  2 root root 4096 Aug 16 22:11 . dr-xr-x--x. 10 root root 4096 Aug 16 22:07 .. -rw-rw-r--.  1 a    a       0 Aug 16 22:11 file1 [a@localhost test]$ mkdir folder1 [a@localhost test]$ ls -la total 12 drwsr-xrwx.  3 root root 4096 Aug 16 22:11 . dr-xr-x--x. 10 root root 4096 Aug 16 22:07 .. -rw-rw-r--.  1 a    a       0 Aug 16 22:11 file1 drwxrwxr-x.  2 a    a    4096 Aug 16 22:11 folder1 [a@localhost test]$   As you can see, it seems the files and folders the user a created in /root/test didn't inherit the owner and group of it. The owner and group is a and not root. Are there any problems with my testing? I'm new in Linux.
Why does the SUID bit have no effect when applied to directories in Linux? I clearly see that I can set it with 'chmod u+s'. But why does it not have "any" effect. What is the reason for implementing a way to SET it but not implementing any effect?
Do questions about specific StackOverflow implementation details belong on SO or Meta? has several discussion comments going back and forth about whether the question belongs on SO or Meta.  The question is asking about how a specific feature of the site is implemented from a coding perspective (so that the OP might duplicate it in their own implementation), which can make it a legitimate programming question.  According to the Meta FAQ: "If your "question is about ... Stack Overflow / The core Stack Exchange engine", it should be asked here.  Here are some similar example questions on Meta:         Where do these questions belong? Does the use of words such as 'fail', 'wrong', 'incorrect' and 'invalid' have a sufficiently negative impact on a users frame of mind to warrant the prohibition of their inclusion in the error messages generated by typical web forms?  i.e. Should we rephrase examples like these to just use positive words?  'date entered incorrectly'  or  'failed to complete registration, please see below for invalid field entries'  (PS, the examples are there to show use of the words in an error message, not to serve as examples of error messages I would use or things that need correcting in answers, I'm not looking for advice on how to write form error messages, but for information about the effect of certain words on a users frame of mind) Consider:  List&lt;String&gt; someList = new ArrayList&lt;String&gt;(); // add "monkey", "donkey", "skeleton key" to someList     for (String item : someList) {     System.out.println(item); }   What would the equivalent for loop look like without using the for each syntax? I'm having trouble solving a Fitch Style Proof and I was hoping someone would be able to help me.  Premises: p ∧ q  Goal: q ∨ r  Would be an assumption (p ∧ q => q ∨ r) in first step a correct one?   Then, q ∨ r Implication Elimination: 2, 1  Why is it not correct?  Thank you very much for any help! p-value approach - clarify teacher's solution? So I have a question with my teacher's solution below and I'm confused about one of the steps in their solution. I would appreciate some clarification.  Two brands of coffee were compared. Two independent random samples of 50 people each were asked to taste either Brand A or Brand B coffee, and indicate whether they liked it or not. Eighty four percent of the people who tasted Brand A liked it; the analogous sample proportion for Brand B was ninety percent.   (A) At α = 0.01, is there a significant difference in the proportions of individuals who like the two coffees? Use the p-value approach.   So I circled in blue a step where I'm confused about in the teacher's solution. I don't understand why P(Z&lt;-0.89) = 0.2061.   On the z-score table -0.89 is equal to 0.1867 so shouldn't it be that value instead? where did 0.2061 come from? Is it possible that the teacher made an error or am I not understanding something? Does the intersection of two finite index subgroups have finite index? Solve the recurrence $T(n) = 2T(n-1) + n$ ACPI PPC Probe failed. Starting version 219 NVIDIA In my calculator why does $\sqrt4 -2=-8.1648465955514287168521180122928e-39?$ I have tried this on my Windows 7 calculator with $\sqrt9 -3 $ it too gives some weird answer- ie$1.1546388020691628168216106791278e-37$. And so for any $n$(positive) $\sqrt n^2-n= wierd_ .answer$ Why does this happen? In the book Thomas's Calculus (11th edition) it is mentioned (Section 3.8 pg 225) that the derivative $dy/dx$ is not a ratio. Couldn't it be interpreted as a ratio, because according to the formula $dy = f'(x)dx$ we are able to plug in values for $dx$ and calculate a $dy$ (differential). Then if we rearrange we get $dy/dx$ which could be seen as a ratio.   I wonder if the author says this because $dx$ is an independent variable, and $dy$ is a dependent variable, for $dy/dx$ to be a ratio both variables need to be independent.. maybe? I accidentally rsynced .thunderbird to user@host instead of to user@host:/home/user.  Where is .thunderbird now?  Is there a good way to search for the folder? Blender render crash when using subsurf modifiers. How are "Suggested Tags" chosen? After you've typed in a question, you get suggested tags that appear that look like this:        It appears that you need a minimum amount of characters ():     you must have entered a title (any length) and a minimum body length of 220 characters.   But other than that, how are the tags chosen? Is it:   A match of the title/body with other questions (taking the tags from those questions) A match of the title/body with tag excerpts (taking tags with overlap) A match of the title/body with tag wikis (taking tags with overlap) All of the Above None of the Above Other (please explain)   Some additional info from :  The suggested tags seem to only pop up on meta.so (they do not work on regular Stack Overflow, or on other SE sites).  While we're on the topic, why isn't this feature implemented network-wide? Suppose I'm given the mean and one quantile (e.g. the 20% quantile) of a random variable $x$, and I want to find the parameters $\alpha$ and $\beta$ of a Beta distribution that has the same mean and quantile.  Is there an efficient way to do it?    Using just the mean, I know that since $\bar{x} = \frac{\alpha}{\alpha+\beta}$, we have $\beta = \frac{\alpha}{\bar{x}} - \alpha$.  So we only really have one parameter to estimate.  But I'm unsure how to use the quantile information to take the next step.  Maybe there's something I can do with the Incomplete Beta when I know the ratio $\frac{\beta}{\alpha} = \frac{1-\bar{x}}{\bar{x}}$?  I have access to R myself, so I could use a numerical optimizer for this, but ideally I need a method that can be carried out in Excel in someone else's environment.  Excel does have BETA.DIST() and BETA.INV() functions available.  A look-up table would be fine, but a closed-form formula would be better if it's possible. I have an image with a woman, and I need to make an ad (size 260mmx125mm). I want to put the woman to the left side, but then right side becomes empty. So, how I should solve the problem? I have picked the color from image, but it is definitely different than in the actual picture.  Should I use the Clone Stamp Tool in Photoshop, or there is a better way to do this?  By the way, it will be used in print, so I need a good quality. How to fix TikZ corners in 3D Am trying to draw a simple rectangle and there seems to be minor issue with two of the endpoints (f and d in the following). I tried line cap=rect as suggested by  but that did not seem to work.  The resulting image:    \documentclass{standalone} \setlength\PreviewBorder{5pt}%  \usepackage{tikz}  \newcommand*{\Width}{2.0} \newcommand*{\Height}{3.0} \newcommand*{\Depth}{1.0}  \begin{document} \begin{tikzpicture}%     \coordinate (A) at ( 0,       0,     \Depth);%     \coordinate (B) at (\Height,  0,     \Depth);%     \coordinate (C) at (\Height,  0,      0);%     \coordinate (D) at (\Height, \Width,  0);%     \coordinate (E) at ( 0,      \Width,  0);%     \coordinate (F) at ( 0,      \Width, \Depth);%     \coordinate (G) at (\Height, \Width, \Depth);%     \coordinate (H) at ( 0,       0,      0);%     %     \draw [blue, ultra thick,line cap=rect]%         (A) -- (B) -- (C) -- (D) -- (E) -- (F) -- cycle;%     \draw [blue, ultra thick,line cap=rect]%         (B) -- (G) -- (F) -- (E) -- (D) -- (G) -- cycle;%      \path (D)  [right] node {$d$};% Problem Point 1     \path (F)  [left ] node {$f$};% Problem Point 2 \end{tikzpicture}% \end{document}   This problem about  seems related, but I do not understand how to adapt that to my problem. I want to assign a class attribute via a string object - but how?  Example:  class test(object):   pass  a = test() test.value = 5 a.value # -&gt; 5 test.__dict__['value'] # -&gt; 5  # BUT: attr_name = 'next_value'  test.__dict__[attr_name] = 10 # -&gt; 'dictproxy' object does not support item assignment apt-get cannot connect to Ubuntu archives I just installed a fresh version of Ubuntu 19.10 today, and the first thing I decided to do was to install GNU Screen, using sudo apt-get install screen. my output was: Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package screen  I figured the package archives were not quite updated as it was a clean install so I tried sudo apt-get update. This is what I got: Get:1 http://security.ubuntu.com/ubuntu eoan-security InRelease [97.5 kB]       Err:2 http://au.archive.ubuntu.com/ubuntu eoan InRelease   Cannot initiate the connection to au.archive.ubuntu.com:80 (2001:388:30bc:cafe::beef). - connect (101: Network is unreachable) Could not connect to au.archive.ubuntu.com:80 (202.158.214.106), connection timed out Err:3 http://au.archive.ubuntu.com/ubuntu eoan-updates InRelease      Cannot initiate the connection to au.archive.ubuntu.com:80 (2001:388:30bc:cafe::beef). - connect (101: Network is unreachable) Err:4 http://au.archive.ubuntu.com/ubuntu eoan-backports InRelease   Cannot initiate the connection to au.archive.ubuntu.com:80 (2001:388:30bc:cafe::beef). - connect (101: Network is unreachable) Fetched 97.5 kB in 31s (3,106 B/s) Reading package lists... Done Building dependency tree        Reading state information... Done All packages are up to date. W: Failed to fetch http://au.archive.ubuntu.com/ubuntu/dists/eoan/InRelease  Cannot initiate the connection to au.archive.ubuntu.com:80 (2001:388:30bc:cafe::beef). - connect (101: Network is unreachable) Could not connect to au.archive.ubuntu.com:80 (202.158.214.106), connection timed out W: Failed to fetch http://au.archive.ubuntu.com/ubuntu/dists/eoan-updates/InRelease  Cannot initiate the connection to au.archive.ubuntu.com:80 (2001:388:30bc:cafe::beef). - connect (101: Network is unreachable) W: Failed to fetch http://au.archive.ubuntu.com/ubuntu/dists/eoan-backports/InRelease  Cannot initiate the connection to au.archive.ubuntu.com:80 (2001:388:30bc:cafe::beef). - connect (101: Network is unreachable) W: Some index files failed to download. They have been ignored, or old ones used instead.  I'm really not sure why it would be doing this, other than maybe some first-use hiccups? The computer is definitely connected to the internet, as I am writing this from that machine, and I have tried running the commands after rebooting and it still gives the errors. I can't seem to be able to connect to au.archive.ubuntu.com at all. ping au.archive.ubuntu.com just sits there without a response. If anyone could help, that would be great! If any extra information is required I'd be happy to edit it into the question. Image viewer without large window borders I am looking for an image viewer software without very large window borders. I don't need any type of toolbar, just a simple image viewer.   It would also be fine if there is no top bar to close, minimize or maximize window. Some websites and textbooks refer to $$\Delta x \Delta p \geq \frac{\hbar}{2}$$ as the correct formula for the uncertainty principle whereas other sources use the formula $$\Delta x \Delta p \geq \hbar.$$ Question: Which one is correct and why?  The latter is used in the textbook "Physics II for Dummies" (German edition) for several examples and the author also derives that formula so I assume that this is not a typing error.  This is the mentioned derivation:     $\sin \theta = \frac{\lambda}{\Delta y}$      assuming $\theta$ is small:      $\tan \theta = \frac{\lambda}{\Delta y}$      de Broglie equation:      $\lambda = \frac{h}{p_x}$      $\Rightarrow \tan \theta \approx \frac{h}{p_x \cdot \Delta y}$      but also:      $\tan \theta = \frac{\Delta p_y}{p_x}$      equalize $\tan \theta$:      $\frac{h}{p_x \cdot \Delta y} \approx \frac{\Delta p_y}{p_x}$      $\Rightarrow \frac{h}{\Delta y} \approx \Delta p_y \Rightarrow \Delta p_y \Delta y \approx h$      $\Rightarrow \Delta p_y \Delta y \geq \frac{h}{2 \pi}$      $\Rightarrow \Delta p \Delta x \geq \frac{h}{2 \pi}$   So: Which one is correct and why?