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1. Jan Schaumann (jschauma@mstdn.social)'s status on Tuesday, 26-Nov-2024 15:58:24 UTC Jan Schaumann

   Advanced #Programming in the #UNIX Environment

   `umask` and file modes explained in one slide

   • Jan Schaumann (jschauma@mstdn.social)'s status on Tuesday, 26-Nov-2024 15:58:23 UTC Jan Schaumann

     in reply to

     Advanced #Programming in the #UNIX Environment

     Week 4, The Unix Filesystem

     We begin a closer look at the Unix Filesystem (#UFS) and the Berkeley Fast Filesystem (FFS). We see how the filesystem structures the disk and organizes files and directories, visualize the concept of hard links, and observe how operations on a directory are independent of the files and their data.

     https://youtu.be/kY4JAXYyByQ

     #apue

   • Jan Schaumann (jschauma@mstdn.social)'s status on Tuesday, 26-Nov-2024 15:58:24 UTC Jan Schaumann

     in reply to

     Advanced #Programming in the #UNIX Environment

     Week 3 bridge to week 4: Union Mounts and Whiteout Files

     We describe the concept of union mounts and see what happens when a file in the upper layer is removed while the same file still exists in the lower layer: a whiteout file is created to cover up the lower file.

     https://youtu.be/MkFExG9jhEE

     #apue

   • Jan Schaumann (jschauma@mstdn.social)'s status on Tuesday, 26-Nov-2024 15:59:02 UTC Jan Schaumann

     in reply to

     Advanced #Programming in the #UNIX Environment

     Week 4, Directory Size

     We dive deep into the structure of the directory on a traditional Unix File System and see how its size is independent of the file _sizes_ of its entries, but dependent on the _filename lengths_. We'll also use hexdump(1) to cheat a bit and look at the directory structure on disk. (This works on #NetBSD. #Linux doesn't let you read(2) a directory; you can use debugfs(8) there.)

     https://youtu.be/gY0SE-71LZA

   • Jan Schaumann (jschauma@mstdn.social)'s status on Tuesday, 26-Nov-2024 15:59:03 UTC Jan Schaumann

     in reply to

     Advanced #Programming in the #UNIX Environment

     The #UFS File System (from the -- by now old -- "#Solaris Internals" book)

     https://ptgmedia.pearsoncmg.com/images/0131482092/samplechapter/mcdougall_ch15.pdf

   • Jan Schaumann (jschauma@mstdn.social)'s status on Tuesday, 26-Nov-2024 15:59:04 UTC Jan Schaumann

     in reply to

     Advanced #Programming in the #UNIX Environment

     Week 4, Directories

     We take a look at how directories are created and removed, how to iterate directory entries using opendir(2), readdir(2) / getdents(2), and how to move around the filesystem hierarchy (with a quick hint of fts(3)). We also figure out why the 'cd' command must be a shell builtin in order to work, despite some systems providing a useless /usr/bin/cd (for some interpretation of #POSIX compliance).

     https://youtu.be/xZ7dNXZ58G8

     #apue

   • Jan Schaumann (jschauma@mstdn.social)'s status on Tuesday, 26-Nov-2024 15:59:05 UTC Jan Schaumann

     in reply to

     Advanced #Programming in the #UNIX Environment

     Week 4, Links

     We'll take a look at the system calls used to create, remove, and rename both hard- and symbolic links and when disk blocks are actually free'd. We'll compare expected output against trivial implementations of the ln(1) and mv(1) commands.

     https://youtu.be/0l8o2goJ1kc

     #apue