SYS

Process Signals

kill -SIGUSR1 $(pidof daemon)
# graceful reload config

Understanding Unix signal handling for daemon management and graceful shutdowns.

NET

Socket Binding

bind(fd, (struct sockaddr*)&addr,
     sizeof(addr));

Low-level TCP socket creation and the nuances of port reuse in production.

MEM

Stack Allocation

char buf[4096];  // stack frame
// no malloc, no free, no leak

When and why to prefer stack allocation over heap in performance-critical paths.

FS

Inode Internals

stat(path, &sb);
printf("ino: %lu", sb.st_ino);

Filesystem metadata structures and how hard links share inode references.

CRYPTO

Hash Chains

h = sha256(h || nonce);
// chain integrity verification

Building tamper-evident logs using iterative cryptographic hash chains.

ASM

Syscall ABI

mov rax, 1    ; sys_write
mov rdi, 1    ; stdout
syscall

x86_64 Linux syscall convention — registers, numbers, and the kernel boundary.