Keyboard shortcuts

Press ← or → to navigate between chapters

Press S or / to search in the book

Press ? to show this help

Press Esc to hide this help

ctrlaltdel

Set the function of the Ctrl-Alt-Del key combination.

Synopsis

ctrlaltdel [hard|soft]

Operation

  • No argument: Reads /proc/sys/kernel/ctrl-alt-del and prints hard (1) or soft (0).
  • hard: Writes 1 to /proc/sys/kernel/ctrl-alt-del. Ctrl-Alt-Del will immediately reboot the system without syncing.
  • soft: Writes 0 to /proc/sys/kernel/ctrl-alt-del. Ctrl-Alt-Del will send SIGINT to PID 1 (init), which handles a graceful shutdown.

Equivalent to calling reboot(2) with LINUX_REBOOT_CMD_CAD_ON (hard) or LINUX_REBOOT_CMD_CAD_OFF (soft), but uses /proc/sys/kernel/ctrl-alt-del for simplicity.

Inputs

  • /proc/sys/kernel/ctrl-alt-del — read to query current state

Outputs

  • /proc/sys/kernel/ctrl-alt-del — written to change state
  • stdout: prints hard or soft when querying

Command-line options

OptionDescription
hardSet Ctrl-Alt-Del to immediately reboot
softSet Ctrl-Alt-Del to send SIGINT to init
(none)Display current setting
-h, --helpDisplay help
-V, --versionDisplay version

Exit codes

CodeMeaning
0Success
1Failure (permission denied, invalid argument)

Permissions

Requires root (or CAP_SYS_ADMIN) to change the setting. Querying is available to any user who can read /proc/sys/kernel/ctrl-alt-del.