Manyak writes:
> Then again, the SysReq command also hasn't been used for anything
> since the IBM S370 Terminals.
Well, Linux has support for it, and I'm making occasional use of it.
It's quite convenient when a process is eating up all memory and the
userland becomes unresponsive. SysRq- still works nicely
in this situation since it traps directly into the Kernel.
,----[ Documentation/sysrq.txt.gz ]
| * What is the magic SysRq key?
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| It is a 'magical' key combo you can hit which the kernel will respond
| to regardless of whatever else it is doing, unless it is completely
| locked up.
| [...]
| * What are the 'command' keys?
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| 'r' - Turns off keyboard raw mode and sets it to XLATE.
|
| 'k' - Secure Access Key (SAK) Kills all programs on the current virtual
| console. NOTE: See important comments below in SAK section.
|
| 'b' - Will immediately reboot the system without syncing or unmounting
| your disks.
|
| 'c' - Will perform a kexec reboot in order to take a crashdump.
|
| 'o' - Will shut your system off (if configured and supported).
|
| 's' - Will attempt to sync all mounted filesystems.
|
| 'u' - Will attempt to remount all mounted filesystems read-only.
|
| 'p' - Will dump the current registers and flags to your console.
|
| 't' - Will dump a list of current tasks and their information to your
| console.
|
| 'm' - Will dump current memory info to your console.
|
| 'v' - Dumps Voyager SMP processor info to your console.
|
| '0'-'9' - Sets the console log level, controlling which kernel messages
| will be printed to your console. ('0', for example would make
| it so that only emergency messages like PANICs or OOPSes would
| make it to your console.)
|
| 'f' - Will call oom_kill to kill a memory hog process
|
| 'e' - Send a SIGTERM to all processes, except for init.
|
| 'i' - Send a SIGKILL to all processes, except for init.
|
| 'l' - Send a SIGKILL to all processes, INCLUDING init. (Your system
| will be non-functional after this.)
|
| 'h' - Will display help ( actually any other key than those listed
| above will display help. but 'h' is easy to remember :-)
|
`----