Given that users can be added to multiple groups, I'm in a situation where I need to restrict access to an intersection of groups rather than a union or subset of groups for a file.  More concretely, given permission group A and group B, I'd like to restrict access to users who are members of A and B, and not members of A-only or B-only. Current ACL usage allows you to restrict access to users who belong to A or B by adding to the ACL of a file.   The closest I've considered is some kind of nested directory scheme /dir_A/subdir_B/file. Here dir_A directory has execute-only permissions for A and subdir_B has execute-only permissions for B, and file has read-only permissions ACLs for A and B. As I understand this only prevents listing files and does not stop a user with only group A membership of reading the file given the full file path.
Can a Linux user belong to more than one group?  If it is allowed, then one use may access files from two groups, that would be quite nice!  If not, is there any alternative way to have this function?  This issue is not the same as  or
How get eigenvectors without phase jump? What do (lambda) function closures capture? Did the date of Frodo's rescue out of the fire of Mordor have any particular meaning in The Lord of the Rings? Align equation left Here is my split equation:  \documentclass{article} \usepackage{amsmath} \begin{document} \begin{equation} \begin{split} a_{ijk} =&amp; \frac {Pr(M_{I} =2  \&amp;  M_J=1 \&amp; M_K =1 | I=i , J=j , K=k)}{Pr (M_I =1 \&amp; M_J =1 \&amp; M_K=1 | I=i , J=j)} \\             =&amp; \frac {\mu_{ijk211}}{\mu_{ijk111}}\\ \end{split} \end{equation} \end{document}   I want to align this equation to the left. Is this possible in an equation environment? When using QuickLook to quickly look through multiple images (pressing space and then using the arrow keys to navigate), some images will not get displayed by QuickLook when hitting them up a second time (going back for example).   A GIF does a much better job than me showcasing the issue. So here's me previewing a few random images:    I have tried deleting   ~/Library/Preferences/com.apple.QuickLookDaemon.plist ~/Library/Caches/com.apple.QuickLookDaemon/Cache.db ~/Library/Caches/com.apple.QuickLookDaemon32/Cache.db ~/Library/Containers/com.apple.quicklook.ui.helper  and restarting, unfortunately to no avail.  Repairing permissions and restarting the Finder in 32-bit mode, as suggested  by others, don't appear to have any effect on this issue either.  This happens with all kinds of images, no matter their source or format. How can I distribute a native executable for a Python program? Counting the number of surjections. In order to animate a character so that it grabs an object an throws it, I added a Child-Of constrained and keyframed its influence. In the F-curve Editor I can't set the curve which controls the influence to interpolation-mode Constant without changing the other curves (Which should be linear or bezier).   How can the interpolation mode of a curve changed independently? Sharepoint Online/O365 custom fonts Can't install aircrack-ng Whenever I attempt to install aircrack-ng in terminal I get the following error:  Package aircrack-ng is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source However the following packages replace it:   iw  E: Package 'aircrack-ng' has no installation candidate"   I'm new to Ubuntu and so have no idea what to do. Does adverb placement affect meaning? He swam slowly to the island.  He slowly swam to the island.    Some experts say that there is a “slight difference” in meaning. Would you please tell me that difference? Merging columns from two separate files Comment authors are not getting migrated When $f(x+1)-f(x)=f'(x)$, what are the solutions for $f(x)$? The question is:     When $f(x+1)-f(x)=f'(x)$, what are the solutions for $f(x)$?   The most obvious solution is a linear function of the form $f(x)=ax+b$. Is this the only solution?  Edit  I should add that $f:\mathbb R\to\mathbb R$ to the question. I'm using TeXLive 2014. Here's a MWE:  \documentclass{article} \usepackage{tkz-fct}         % Must appear before {thmtools}  \usepackage{thmtools} \declaretheorem{theorem}  \begin{document}   \begin{tikzpicture}     \tkzInit  % No need to even plot anything!   \end{tikzpicture}    \begin{theorem}[A Silly Theorem]     Let $a = 1$. Then $a &gt; 0$.   \end{theorem} \end{document}   The error message is:  ! Extra \endcsname. \kv@processor@default ...fincsname\@xa \endcsname                                                   \csname iftrue\endcsname \... l.12   \begin{theorem}[A Silly Theorem]   If the optional theorem name is removed, all is well. Adding \protect{} doesn't help.  Any idea how to remove this conflict?  Thanks! Error in fontspec (my first question here) I'm using xelatex to compile this code:  \documentclass{book} \usepackage{fontspec}  \begin{document}  %This is a Greek text ``Ελλάδα'' text  \end{document}   and receive this error :  ("C:\Program Files\MiKTeX 2.9\tex\latex\fontspec\fontspec.cfg") ! Undefined control sequence. &lt;argument&gt; \LaTeX3 error:                             Erroneous variable \c__fontspec_shape_n_n_tl used! l.3806 \emfontdeclare{ \emshape, \eminnershape }   My aim is to make LaTeX compile greek letters properly in my pdf, but that's a different issue. When compiling a tex file including references (by Texstudio editor and Miktex distribution) using biblatex with bibtex backend and ieee style, the results of the displayed references in the output pdf is messed up at the "volume" and "issue number" entries as follows:   The volume label "vol." is missing (Ref. 1 &amp; 2 in the given example below). The numeric issue number "3" is missing (Ref. 1 in the given example). The issue number label "no." is displayed although NO input entry was being given (Ref. 2 in the given example).   If it helps, this behavior was noticed after the recent update of Miktex on March 11, 2017, including  package (ver. 1.2a 2017-03-02). As before which, everything was going fine!  So is this issue noticed by someone else? Is there any idea about the reason of such strange act by biblatex?  \documentclass{article} \usepackage{filecontents} \begin{filecontents}{reference.bib}     @article{author1,         author  = "George Green",         title   = "Basic latex",         year    = "2000",         journal = "Sharelatex Journal",         volume  = "10",         number  = "3",         pages   = "100--101"     }     @article{author2,         author  = "Carol White",         title   = "Basic studio",         year    = "2010",         journal = "Club Journal",         volume  = "20",         pages   = "200--201"     } \end{filecontents} \usepackage[backend=bibtex, style=ieee]{biblatex}  \addbibresource{reference.bib} \begin{document}     Hi there! \\     Ref 1 Green \cite{author1}. \\     Ref 2 White \cite{author2}.     \printbibliography  \end{document}   The output is as follows: How to disable battery charging? From the pmset man page:     POWER SOURCE ARGUMENTS      -g with a 'batt' or 'ps' argument will show the state of all attached power sources.      […] Certain Apple battery calibration tools may temporarily disable   battery charging, even though your Apple portable is plugged into AC   power.      Such tools will never surprise you with this behavior; you will know   it's happening. This state will be reflected in an additional line of   output to 'batt' or 'ps' readings, including the pid of the app   inducing this behavior.       'ChargeInhibit':    1432    So, does any piece of publicly available software exist to force the battery not to charge? Where does the question mark go — inside or outside the parentheses? I know that when brackets enclose part of a sentence, the full stop goes outside.     I tripped over this morning. I was distracted by a plane (which turned out to be Superman).   If it's a full sentence, the full stop goes inside.     I tripped over. (I was distracted by a plane that turned out to be Superman.)   What happens when there's a question mark and only part of the sentence is a question?     I tripped over this morning. I was distracted by a plane (or was it Superman?)      (or was it Superman?).      (or was it Superman)?   What happens to the full stop that belongs to the rest of the sentence, and why? Is it possible to identify what the parent program/app is from a running process?