[Verse 1] When the kernel finishes loading all its code Process number one takes control of the road Three systems waiting to answer the call SysV, systemd, BusyBox standing tall Scripts and services need someone to start Init system becomes the beating heart [Chorus] Boot it up, hand it off, kernel to user space SysV scripts, systemd units, BusyBox saves space Run levels, targets, dependencies in line Init systems make everything align From hardware to software, the handoff is clean The best orchestrated startup you've ever seen [Verse 2] SysV init with its numbered run levels Zero through six, each state it develops Shell scripts in order, S for start K for kill when systems depart Sequential loading, one by one Traditional method since Unix begun [Chorus] Boot it up, hand it off, kernel to user space SysV scripts, systemd units, BusyBox saves space Run levels, targets, dependencies in line Init systems make everything align From hardware to software, the handoff is clean The best orchestrated startup you've ever seen [Verse 3] Systemd brings units and parallel might Services and sockets starting up right Targets replace the old run level way Dependencies managed throughout the day Journal logging and D-Bus control Modern approach with a unified goal [Bridge] BusyBox init keeps it simple and small Embedded systems don't need it all Lightweight footprint, minimal code Perfect for when you're space constrained mode [Verse 4] Kernel mounts root, then exec's PID one Hardware detection is finally done User space services begin their dance Network and storage get their chance From bootloader to login prompt bright Init systems make everything right [Chorus] Boot it up, hand it off, kernel to user space SysV scripts, systemd units, BusyBox saves space Run levels, targets, dependencies in line Init systems make everything align From hardware to software, the handoff is clean The best orchestrated startup you've ever seen [Outro] Three different paths but the goal's the same Bringing your system up to play the game Init one takes the kernel's final call And brings user space services to all
← Kernel Configuration Deep Dive | Device Trees: Hardware Description Language →