this post was submitted on 21 Nov 2023
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Linux
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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
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I remember myself asking why directories had x flags in their permissions. Like, you don't execute them. What do they use the x flag for?
There needs to be a Linux kernel fork that when you try to execute a directory executes all programs in the directory. In parallel. Juuuuuuuust to fuck with people who might accidentally execute the
/usr/bindirectory.And if there's a circular symlink, we fork bomb
Or worse… In order. Based on last Modified date. And use that as the basis for some scheduling agent where timing and order of execution is essential.
That's the most evil thing I've heard in awhile, and I would absolutely make use of it anyway.
All you have to do is touch the files in order. Why aren’t you using this touchsched repo here….
Those of us who use the autocd feature of shells "execute" directories all the time. For example I'd type just
/usr/bin RETif I wanted to cd to /usr/bin.For directories, it’s permission to
cdinto it. Read is whether you can list files, and write is remove, rename, or create new files. Don’t ask questions about the secret sticky bitcd as owner lol
The x permission on directories is exactly for this purpose. You can use the directory. You cannot read (requires rx), you cannot write (w), but you can 'cd' and operate on files in the directory.
This is important, you can lock someone out from a directory tree buy not giving them 'x' on the root. So, if your home is rwx------, no one but the owner can do anything in your home. This is effective even if some files and subdirectories have less restrictive permissions.
Does that include root?
Point for you, root is special.
Executing a list read of the inode?
It's necessary if you want to give somebody rw access to a subdirectory but not the parent.
The parent gets "x" and the child gets "rwx".
This way you can have multiple users with their own directories under, say, /var/www/html but restrict access to /var/www/html itself.
If the user doesn't have "x" then they can't see anything in that directory at all.