s6

What s6 is

s6 is a free suite of UNIX programs for process supervision and low-level service administration on POSIX-compliant systems. Its supervision system organizes processes into a tree, provides controls for managing them, and monitors service states. Readiness notifications can form a basis for coordinating services with dependencies. The suite includes s6-log and tools for syslog-like functions, along with utilities for access control and controlled privilege gain without setuid programs. For socket activation, s6 can hold file descriptors so servers can be connected without changes to application code, a specific library, or a different init system. Related projects include s6-linux-init, s6-rc, s6-frontend, and s6-overlay for Docker images. s6 is available under the ISC license. Installation requires a POSIX-compliant system, a standard C development environment, and GNU make 3.81 or later. Building requires skalibs 2.15.1.0 or later; execline is recommended for full functionality. The maker lists release 2.15.1.0 and provides self-contained documentation, a supervision mailing list, an OFTC IRC channel, and a contact email.