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  • Ah, it's just a linear combination of the individual bitmasks. Thanks very much.
    – user001
    Commented Jan 7, 2012 at 18:08
  • One follow-up: If nothing happens when I do Alt+SysRq+(a command key), then I suppose this means that sysrq was not enabled when the kernel was installed. Is there a simple way to check whether sysrq is enabled or not (e.g., can I find the status of CONFIG_MAGIC_SYSRQ somewhere)?
    – user001
    Commented Jan 7, 2012 at 18:14
  • 3
    I added a possible way to check for CONFIG_MAGIC_SYSRQ. Commented Jan 7, 2012 at 18:27
  • Thanks. Worked for me on Debian as well. The output: CONFIG_MAGIC_SYSRQ=y CONFIG_MAGIC_SYSRQ_DEFAULT_MASK=0x01b6 (01b6 in hex is 438 in decimal). I suppose the y means it has been enabled. Would give 2 up-votes if I could.
    – user001
    Commented Jan 7, 2012 at 18:28
  • 1
    On many Linux distros, the configuration is kept in the kernel itself, not in /boot, so the check command would be zgrep SYSRQ /proc/config.gz (or gunzip -c /proc/config.gz | grep SYSRQ). Commented Jan 7, 2012 at 19:16