EPERM and EACCES errors — file permission issues in Node.js

Node.js file operations fail with EPERM (operation not permitted) or EACCES (permission denied). Common with npm global installs, Docker volumes, and CI/CD pipelines.

(1) npm global: never use sudo with npm. Fix with: mkdir ~/.npm-global, npm config set prefix '~/.npm-global', add to PATH. Or use nvm/fnm which handles this automatically. (2) Docker: match container user UID/GID with host user for bind mounts. (3) File locks: another process has the file open (EPERM on Windows). (4) Read-only file system in Docker: check volume mount options. (5) CI: ensure the runner user owns the workspace directory.

Unix file permissions (owner/group/other) restrict access. Node.js runs as the current user and inherits their permissions. Docker containers run as root by default but host files retain their original permissions.