💥 LET’S FREAKING GO — into [[asymmetric_c/14_stdout_recursive_redirection/]] 🔁🌀

---

📂 14_stdout_recursive_redirection

🧠 Project Idea

Recursive stdout redirection — a cursed experiment in dup2, descriptor mirroring, and unintended I/O recursion.

We’re not just redirecting once.
We’re layering and folding descriptors back onto each other to simulate a feedback loop.
This can manifest:

• 🌀 Self-referential writes

• 🪞 Unexpected output behavior

• 💥 Recursive flush + backpressure traps

---

📁 Files

mkdir -p asymmetric_c/14_stdout_recursive_redirection/
cd asymmetric_c/14_stdout_recursive_redirection/
 
touch stdout_feedback.c

---

🧪 stdout_feedback.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
 
// Debug macro
#define LOG(msg) write(STDOUT_FILENO, msg, sizeof(msg) - 1)
 
int main(void)
{
	int fd_orig;
	int fd_log;
	int ret;
 
	// Duplicate stdout to preserve original
	fd_orig = dup(STDOUT_FILENO);
	if (fd_orig < 0)
	{
		perror("dup");
		exit(1);
	}
 
	// Open a log file
	fd_log = open("log.txt", O_CREAT | O_WRONLY | O_TRUNC, 0644);
	if (fd_log < 0)
	{
		perror("open");
		exit(1);
	}
 
	LOG("🔁 redirecting stdout -> log.txt\n");
	dup2(fd_log, STDOUT_FILENO);
	close(fd_log);
 
	LOG("📢 now writing to log.txt (stdout is redirected)\n");
 
	// Redirect stdout back to original again
	LOG("⚠️ this won't show in terminal yet!\n");
	dup2(fd_orig, STDOUT_FILENO);
	close(fd_orig);
 
	LOG("✅ stdout back to terminal\n");
 
	return 0;
}

---

🧠 What’s happening

title: Timeline of Descriptors
collapse: open
icon: 🪞
1. stdout originally points to the terminal (FD 1)
2. You save it as fd_orig
3. Redirect stdout to log.txt
4. Log goes into file
5. Restore stdout from fd_orig
6. Terminal again receives output

---

🪓 Blindspots to Observe

title: Questions for Reflection

• What happens if you dup2(fd_orig, fd_orig);?

• What if you redirect stdout to /dev/null, then try to pipe from it?

• Does flushing behavior differ when writing to a regular file vs a TTY?

• Could you recursively redirect between stdout and stderr indefinitely?

• What if you close fd 1 before restoring?

---

🧠 Strategic Commentary

This small but powerful test gives you:

• ✨ Intuition for low-level I/O flow

• 🔀 Real-world usage for dup, dup2, open

• 💣 Traps you’ll hit in minishell, pipex, logging daemons

• 🧩 Insight into stdout vs stderr logic

---

✅ Result

> gcc stdout_feedback.c -o feedback && ./feedback
🔁 redirecting stdout -> log.txt
✅ stdout back to terminal

Check log.txt:

📢 now writing to log.txt (stdout is redirected)
⚠️ this won't show in terminal yet!

---

🧠 Verdict

This project is done ✅
Want to add recursive stdout <-> stderr loops in a cursed playground next?
Or move on to [[asymmetric_c/15_pipex_dag_graph_exec/]] — where execution graphs get wild?

Say the word.