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AIX Version 4.3 Commands Reference, Volume 2

halt or fasthalt Command


Stops the processor.


{ halt | fasthalt } [ -l ] [ -n ] [ -p ] [ -q ] [ -y ]


The halt command writes data to the disk and then stops the processor. The machine does not restart. Only a root user should run this command. Do not use this command if other users are logged into the system. If no other users are logged in, the halt command can be used. Use the halt command if you are not going to restart the machine immediately. When the message ....Halt completed.... is displayed, you can turn the power Off.

The halt command logs the shutdown using the syslogd command and places a record of the shutdown in /var/adm/wtmp, the login accounting file. The system also writes an entry into the error log which states that the system was shut down.

The fasthalt command stops the system by calling the halt command. The fasthalt command provides BSD compatibility.


-l Does not log the halt in the accounting file. The -l flag does not suppress accounting file update. The -n and -q flags imply the -l flag.
-n Prevents the sync before stopping.
-p Halts the system without a power down.
Note: The -p flag will have no effect if used in combination with flags not requiring a permanent halt. Power will still be turned off if other operands request a delayed poweron and reboot
-q Causes a quick halt.
-y Halts the system from a dial-up operation.


  1. To halt the system without logging the halt in the accounting file, enter:
    halt -l 
  2. To halt the system quickly, enter:
    halt -q
  3. To halt the system from a dial-up, enter:
    halt -y


/etc/rc Specifies the system startup script.
/var/adm/wtmp Specifies the login accounting file.

Related Information

The fastboot command,fsck command, rc command, shutdown command, sync command.

The syslogd daemon.

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