T49 Dec 24, 2025 2 min read

Stdout/stderr

The standard output and standard error streams of a process, typically file descriptors 1 and 2.

Definition

Stdout and stderr are the standard output and standard error streams of a process.

In Unix-like systems they are typically:

  • stdout: file descriptor 1
  • stderr: file descriptor 2

Why they matter in production

Many modern systems treat stdout and stderr as the logging interface.

Your container runtime or supervisor captures these streams, stores them, and forwards them to log aggregation.