Red Hat ENTERPRISE LINUX 5 - DEPLOYMENT Deployment Manual page 72

Chapter 3. The proc File System
• p — Outputs all flags and registers to the console.
• t — Outputs a list of processes to the console.
• m — Outputs memory statistics to the console.
• 0 through 9 — Sets the log level for the console.
• e — Kills all processes except init using SIGTERM.
• i — Kills all processes except init using SIGKILL.
• l — Kills all processes using SIGKILL (including init). The system is unusable after issuing this
System Request Key code.
• h — Displays help text.
This feature is most beneficial when using a development kernel or when experiencing system
freezes.
Caution
The System Request Key feature is considered a security risk because an unattended
console provides an attacker with access to the system. For this reason, it is turned off
by default.
Refer to /usr/share/doc/kernel-doc-<version>/Documentation/sysrq.txt for more
information about the System Request Key.
• sysrq-key — Defines the key code for the System Request Key (84 is the default).
• sysrq-sticky — Defines whether the System Request Key is a chorded key combination. The
accepted values are as follows:
• 0 — Alt+SysRq and the system request code must be pressed simultaneously. This is the
default value.
• 1 — Alt+SysRq must be pressed simultaneously, but the system request code can be pressed
anytime before the number of seconds specified in /proc/sys/kernel/sysrq-timer
elapses.
• sysrq-timer — Specifies the number of seconds allowed to pass before the system request code
must be pressed. The default value is 10.
• tainted — Indicates whether a non-GPL module is loaded.
• 0 — No non-GPL modules are loaded.
• 1 — At least one module without a GPL license (including modules with no license) is loaded.
• 2 — At least one module was force-loaded with the command insmod -f.
• threads-max — Sets the maximum number of threads to be used by the kernel, with a default
value of 2048.
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