$ Linux Command

System

telinit

Change the system runlevel or send signals to init.

initrunlevelsystemdsysvinit

Additional Notes

telinit communicates with the init process (PID 1) to change the system's runlevel or send control signals. On SysV-init systems, it changes the operating mode by signaling the init daemon, which then starts or stops services according to the runlevel definitions in /etc/inittab.

On systemd-based systems, telinit is a compatibility wrapper that maps traditional runlevel requests to systemd targets. For example, telinit 3 becomes systemctl isolate multi-user.target, and telinit 5 maps to graphical.target. This allows scripts and administrators familiar with SysV commands to continue using telinit on modern systems.

Syntax

telinit [runlevel | signal]

Parameters

  • runlevel: A single digit 0-6, or the characters S/s for single-user mode, a/b/c for custom runlevels.
  • signal: Alternatives like q (reload configuration), u (re-exec init).

Common Runlevels

  • 0: Halt/shutdown the system.
  • 1 or s/S: Single-user mode (maintenance/rescue).
  • 2: Multi-user mode (without network, sometimes without GUI).
  • 3: Multi-user mode with networking (text mode).
  • 4: Undefined/custom.
  • 5: Multi-user mode with GUI (X11).
  • 6: Reboot the system.

Special Options

  • q: Have init re-examine /etc/inittab (SysV). On systemd, this is a no-op.
  • u: Re-exec the init daemon (without changing runlevel).

Examples

telinit 1

Switch to single-user maintenance mode.

telinit 3

Switch to multi-user text mode.

telinit 5

Switch to graphical mode.

telinit 6

Reboot the system.

telinit q

Have init re-read its configuration (SysV only).

telinit u

Re-exec the init process (for updating init itself without reboot).

Practical Notes

  • On systemd systems, telinit and init are symbolic links to systemctl.
  • The shutdown, halt, poweroff, reboot commands are preferred for stopping the system.
  • Runlevel 2 is distribution-specific: some treat it the same as 3, others do not.
  • Use runlevel to check the current and previous runlevel.
  • In container environments, telinit may not be available or may have no effect.
  • The traditional /etc/inittab file is ignored by systemd.