On Fri, Mar 2, 2012 at 20:20:11 +0100, vladz wrote:
> On Fri, Mar 02, 2012 at 02:29:33PM +0100, Julien Cristau wrote:
> > I'm not convinced the chown can be removed. And 'mkdir -m 1777 foo' is
> > not any more atomic than 'mkdir foo && chmod 1777 foo'.
>
> The command "mkdir -m" calls the mkdir() syscall, and its second
> argument seems to be the mode.
>
> $ man 2 mkdir
> [...]
> int mkdir(const char *pathname, mode_t mode);
>
> Maybe I'm wrong, but this is what I call an atomic way to create and set
> permissions (ie. two operations in a unique syscall). For example:
>
> $ strace mkdir -m 222 /tmp/foo
> [...]
> mkdir("/tmp/foo", 0222) = 0
>
the second argument to mkdir obeys umask, so you end up doingmkdir() open() fstat() fchmod() as far as I can tell. > > hmm, how about this: > > > >mkdir -p /tmp/.X11-unix > >chown -h root:root /tmp/.X11-unix > >stat=$(LC_ALL=C stat -c '%u %g %F' /tmp/.X11-unix) > >if [ "$stat" != '0 0 directory' ]; then > > exit 1 > >fi > >chmod 1777 /tmp/.X11-unix > > This would work (even if it uses chmod), but wasn't the Bash approach (test > with "-O", "-G" and "-d") simpler than using "stat"? > test -d follows symlinks... the problem with stat(1) is it's on /usr so I'd have to make this script depend on $remote_fs. Which shouldn't be a problem, but is still a bit annoying. Cheers, Julien
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