Expert · Module 10 · Lesson 12 of 12
Device Files, ioctl, sysfs, and procfs Interfaces
Understand how user-space programs communicate with kernel and device subsystems through special files, ioctl contracts, and virtual filesystems.
Pro — members onlyAbout 18 minutes
By the end you can
- Distinguish character devices, block devices, and virtual filesystems
- Explain ioctl request and data-layout contracts
- Read sysfs and procfs without treating them as ordinary disk files
- Validate user/kernel boundary data
Builds on File Descriptors and Kernel File Tables, Linux procfs, ptrace, and Core-Dump Debugging.
01 · A question first
A path such as `/dev/null` has no ordinary disk contents, yet `open` and `read` work. What object does the file descriptor actually represent?
Make a guess before you read on.
02 · The idea
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What's inside
- Special files
- ioctl contracts
- Define and call a versioned ioctl
- sysfs and procfs
- Where it is used
- Operational checklist
- Boundary cases
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