This is a complete lesson on Linux System Programming: Working with Files. Perfect for Operating Systems, Linux System Programming, C Programming, Computer Science, and Software Engineering courses at the college, university, or technical-training level.

The lesson includes clear explanations, diagrams, file structure details, system call usage, permissions, links, major device files, inode concepts, and multiple hands-on C programming examples.

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✨✨ What This Lesson Covers ✨✨

Linux File Concepts

✔ Everything is treated as a file
✔ Unified file interface for devices and peripherals
✔ Directories as special files
✔ File properties stored in inode
✔ Viewing inode numbers

Links in Linux

✔ Hard links

✔ Soft (symbolic) links
✔ Differences between hard and soft links
✔ inode behavior for each link type
✔ Restrictions on hard links
✔ ln and ln -s demonstrations

File Types & Identification

✔ Using ls -l to identify file types
✔ Meaning of leading characters:
— - regular file
— d directory
— l soft link
— p FIFO/pipe
— s socket
— c character device
— b block device
✔ Exploring dev directory

Mounting File Systems

✔ Mounting CD-ROM
✔ Mounting ISO files
✔ Mounting FAT32 partitions
✔ Mounting NTFS partitions
✔ Unmounting devices

Linux File System Architecture

✔ Hierarchical view of Linux system layers

✔ User-space vs kernel-space roles
✔ System calls vs library functions
✔ Device drivers and dev entries

File Descriptors

✔ What file descriptors are
✔ Standard input (0), output (1), and error (2)
✔ How programs receive new file descriptors

Low-Level File Access (System Calls)

✔ write() — writing raw bytes to a file descriptor

✔ First example program: printing text to standard output

✔ read() — reading bytes from file descriptors

✔ simple_read.c — copying bytes from input to output

✔ Using pipes and redirection with the example program

Opening Files with open

✔ open() function formats

✔ Access modes: read, write, read/write

✔ File creation permissions (mode values)

✔ Permission flags for owner, group, and others

✔ Example: creating a file with specific permissions

File Permissions & umask

✔ How umask affects new file permissions

✔ Calculating octal permission values

✔ Using chmod to modify permissions

✔ Using chown to change ownership

Closing Files & ioctl

✔ close system call

✔ Purpose of ioctl

✔ Example: controlling keyboard LEDs

Process Information in proc

✔ Each running process has a directory under proc

✔ Viewing a process’s info using its PID

✔ Inspecting file descriptors of a running process

✔ Viewing command-line arguments for a process

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✨✨ Formats Included ✨✨

✯ PPTX (fully editable)
✯ PDF (clean, print-friendly version)

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✨✨ What This Resource Includes ✨✨

✯ Clear explanations of Linux’s file model
✯ inode, links, and file type diagrams
✯ Practical demonstrations of mount commands
✯ Detailed walkthroughs of:
— read
— write
— open
— close
— ioctl
✯ Hands-on C programs (system call examples)
✯ File permissions and umask tables
✯ proc system exploration
✯ Fully editable high-quality slides
✯ Ideal for classroom or lab-based teaching

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✨✨ Perfect For ✨✨

✯ Operating Systems classes

✯ Linux system programming courses
✯ C programming and systems courses
✯ Computer Science & Engineering programs
✯ Technical training, bootcamps, and labs
✯ Students preparing for system-level programming tasks

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✨✨ Who Is This For? ✨✨

✯ Teachers needing a ready-to-teach Linux file-system lesson
✯ Students learning low-level Linux programming
✯ Learners preparing for OS or system programming coursework
✯ Tutors teaching Linux, system calls, and file management

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