SGI System Maintenance Menu



System Maintenance Menu

     1   Start System

     2   Install System Software

     3   Run Diagnostics

     4   Recover System

     5   Enter Command Monitor

     6   Select Keyboard Layout

About the Standalone Shell (sash)

The Command Monitor has been designed to keep it independent of operating systems and as small as possible. Therefore, the Command Monitor cannot directly boot files residing in IRIX or other operating system file trees. However, the Command Monitor provides a two-level boot mechanism that lets it load an intermediary program that understands filesystems; this program can then find and load the desired boot file. The program is called the standalone shell, and is referred to as sash. sash is a reconfigured and expanded version of the Command Monitor program, and includes the modules needed to handle operating system file structures. It also has enhanced knowledge about devices.

After the system software is installed, a copy of sash is located in the volume header of the first disk. The header contains a very simple file structure that the Command Monitor understands. You can also boot sash from tape or across the network.

Booting the Standalone Shell (sash)

To boot sash from your disk:

1.Shut down the system

2.When you see the message:

Starting up the system...


To perform system maintenance instead, press Esc

Press the Esc key. You may have to enter your system's Command Monitor password, if your system has one. You see a menu similar to the following:

System Maintenance Menu

(1) Start System

(2) Install System Software

(3) Run Diagnostics

(4) Recover System

(5) Enter Command Monitor

3.Select option 5, Enter Command Monitor from the System Maintenance Menu. You see the following message and prompt:

Command Monitor. Type "exit" to return to the menu.


4.Enter the command:

boot -f sash

sash operates in interactive command mode. You see the SASH prompt:


To use the multilevel boot feature, set the PROM environment variable bootfile to refer to a specific copy of sash. In normal configurations, setting bootfile to dksc(0,0,8)sash tells the Command Monitor to load sash from the SCSI disk controller 0, disk unit 0, partition 8 (the volume header). Use this syntax:

setenv bootfile "dksc(0)disk(1)partition(8)sash"

Then issue a boot command, as in this example for a SCSI drive:

boot dksc()unix initstate=s

The following actions take place:

boot loads dksc(0)disk(0)partition(8)sash, as specified by bootfile, since the boot command doesn't contain a -f argument. (A -f argument overrides the default specified by bootfile.)

sash gets two arguments: dksc()unix and initstate=s, which brings the system up in single-user mode. (Note that the Command Monitor removes the leading hyphen [-] from any argument, so if you use the next layer of software, and need an argument with a leading hyphen, put two hyphens in front of it.)

sash loads the file specified by the first argument (dksc()unix) and passes the next argument to that file.

Do not issue the auto command from sash with the bootfile set as shown above. If you do, the system tries to boot sash over itself and exits with an error.

To be able to use the auto command from sash, set bootfile to refer to the kernel, for example, dksc()unix. Even better, return to the PROM level to use the auto command.