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This article mainly shows you "what are the common faults of the Unix system", the content is simple and clear, and I hope it can help you solve your doubts. Let the editor lead you to study and learn the article "what are the common faults of the Unix system?"

First, after turning on the power of the computer, the following message appears on the console screen: boot not found cannot open stage 1 boot failure:error loading hd (40) / boot, and then crash.

Analysis: this indicates that the Boot file in the system root directory is missing or cannot be found. The Boot file is an interactive program used to load and execute UNIX programs, which is mainly used to load and execute the core of the UNIX operating system. During the boot process, Boot will read / etc/default/boot, display the boot process information, load and execute / Unix, so when the Boot file is lost or can not be found, it will cause the system boot failure.

Solution:

If the Boot file is missing:

1. Boot to a boot disk (emergency floppy disk or installation CD).

two。 Type hd (40) unix at the system boot prompt, which is used to load the Unix core from the hard drive. Then enter the root user's password and enter single-user mode, where the superuser prompt #.

3. To unmount the Boot file system, execute the command: umount / stand.

4. To mount the Boot file system, execute the command: mount / stand. (note: after the SCO Openserver 5.0.5 system boots, the / stand file system is set to read-only, and the properties cannot be changed, so use this method to make the / stand directory writable.)

5. Install the Boot floppy disk into the system with the command, execute the command: mount / dev/fd0135ds18 / mnt, and then use the command: cp / mnt/boot / stand to copy the Boot file to the / stand directory.

6. Uninstall the boot disk with the command umount / dev/fd0135ds18 (or umount / mnt).

7. Remove the boot disk and type the haltsys or reboot command to reboot the system.

8. After the system boots normally, enter the root user and change the owner and group of the / boot file to bin.

If the Boot file cannot be found:

This situation is generally due to the wrong parameters of the hard disk in the Cmos configuration, so you only need to let the system automatically detect the hard disk and correct the parameters.

Second, after the computer is powered on, the following message appears on the console screen: unix not found, and then crash.

Analysis: this indicates that the core of the Unix system is missing. Because / Unix contains a core, a corrupted Unix file will prevent the system from loading the parallel kernel, resulting in a panic.

Solution:

1. Boot with a boot disk.

two。 At the system boot prompt, type fd (60) unix .Z root=hd (42) swap=hd (41) this command is used to load the Unix core from the boot disk and mount the root file system to the hard disk. Then enter the root user's password and enter single-user mode, where the superuser prompt #.

3. Unmount the / stand file system and execute the command: umount / stand.

4. Mount the / stand file system and execute the command: mount / stand.

5. Install the Boot floppy disk into the system and execute the command: mount / dev/fd0135ds18 / mnt.

6. Execute cp / mnt/unix.Z / stand to recover the unix file in the root directory of the hard drive. This operation can compress and copy the Unix kernel file on the boot disk to the hard disk, and the user does not need to decompress the kernel file.

7. Uninstall the boot disk and reboot the system. After the system boots normally, enter the root user and change the owner and group of the Unix file to bin and mem.

Third, after the machine is powered on, type enter at the system boot prompt. When the first screen is refreshed and the second screen is displayed, there are many error messages, such as: INIT:command exec / etc/brc 1 > / dev/console 2 > & & 1 failed to execute, errno=9 (exec of shell failed) and so on.

Analysis: this indicates that the system / bin/sh file is corrupted or missing. Because SH is the interpreter of the shell standard, job control, and restriction commands, a corrupted or missing file will cause the system to fail to boot.

Solution:

1. Boot with a boot disk.

two。 Press enter at the system boot prompt, when prompted to insert the root disk, remove the boot disk and insert the root disk, so that the system is all booted by the emergency boot disk until the prompt: #.

3. Execute the commands mount / dev/hd0root / mnt and cp / bin/sh / mnt/bin/sh to restore the / bin/sh file in the root directory of the hard drive.

4. Uninstall the boot disk, reboot the system, enter the root user after the system boots normally, and change the owner and group of the / boot file to bin.

Fourth, the system can boot and handle daily affairs normally, but every time the computer is turned off, an error message appears on the console screen: / etc/initscript:/etc/uadmin:notfound, and then the system crashes, resulting in a normal shutdown. In this way, you have to clean the file system every time you start, which wastes a lot of time and may seriously damage the file system and paralyze the system.

Analysis: caused by loss or corruption of system file / etc/uadmin.

Solution 1:

1. Register as a root user after the system boots and cleans up the file system.

two。 Under superuser, install the root disk into the system with the command mount / dev/fd0135ds18 / mnt.

3. Copy / etc/uadmin file from floppy disk to hard disk: cp / mnt/etc/uadmin / etc/uadmin.

4. Just uninstall the root disk and change the owner and group of the / etc/uadmin file to bin.

Solution 2:

The first solution is for stand-alone, only emergency disk situation. In the case of multi-computer interconnection, there is actually a more concise way:

1. Use the network to get uadmin files from normal machines with ftp or rcp commands.

two。 Use the floppy disk to use the tar command to get the uadmin file from the normal machine, and then tar into the corresponding path of the failed machine.

5. After the machine is powered on, type the enter key at the system boot prompt. When the first screen is refreshed, the following message appears at the end of the second screen: Kernel:i/o bufs=600k, and then the system hangs.

Analysis: this indicates that the / etc/init file of the system is missing. The Init program starts execution in the final stage of core initialization, and its process number (pid) is 1. 5. The process starts the processes listed in the / etc/inittab file according to certain rules and guides the system to the specified running level. It first reads the initdefault entry in / etc/inittab, and when all the processes are created successfully, the init enters the loop and waits. If the / etc/init file is corrupted, the new process cannot be created, causing the system to hang.

Solution:

1. Boot with a boot disk.

two。 Press enter at the system boot prompt, when prompted to insert the root disk, remove the boot disk and insert the root disk, so that the system is all booted by the emergency boot disk until the prompt: #.

3. Execute the commands mount / dev/hd0root / mnt and cp / etc/init/mnt/etc/init to restore the init file in the root directory of the hard drive.

4. Uninstall the boot disk and reboot the system. After the system boots normally, enter the root user and change the owner and group of the / etc/init file to bin.

6. Prompt when the system starts: NO OS.

Analysis: if the system works normally before, it means that the boot block of the system hard disk is damaged.

Solution:

1. Boot with a boot disk.

two。 Type hd (40) unix at the system boot prompt, which is used to load the Unix core from the hard drive. Then enter the root user's password and enter single-user mode, where the superuser prompt #.

3. Execute the command instbb hd / dev/hd0a to write the boot block partition to the hard disk, and dparam _ w to write the master boot block code to the hard disk.

4. Restart the machine.

Seventh, the system startup can not enter multi-user mode.

Analysis: if the system shows: INIT:can not open / etc/inittab error 2 after startup, the system cannot enter multi-user mode after pressing Ctrl-D, then the / etc/inittab file is missing and / etc/inittab contains instructions for init. When inittab is lost, init cannot execute system startup instructions and the system cannot enter multi-user mode. When Ctrl-D is pressed, the system remains in single-user mode. Because / etc/inittab contains instructions for other parts of the system to refer to, a special / etc/inittab is written to the root file system floppy disk when creating an "emergency disk". Therefore, if there is a problem of / etc/inittab loss, the recovery of the system can not simply copy / etc/inittab from the emergency disk to the hard disk, but copy / etc/conf/cf.d/init.base to / etc/inittab, and then relink the core.

Solution:

1. Start the machine and enter the system maintenance state.

two。 Execute the command cp / etc/conf/cf.d/init.base / etc/inittab, and / etc/conf/cf.d/link_unix-y re-create a new / etc/inittab file. And reboot the system.

/ etc/bcheckrc file is missing.

Analysis: if the system displays the following message during boot: / etc/initscript:/etc/bcheckrc:not found, the / etc/bcheckrc file is missing. This file is a symbolic link file, if the source file is intact, it can be recovered from the source file.

Solution:

1. Start the system and enter system maintenance mode.

two。 Run fsck to clean up the root file system.

3. Execute the command cp / opt/K/SCO/Unix/5.0.5Eb/etc/bcheckrc / etc/bcheckrc, or ln-s / opt/K/SCO/Unix/5.0.5Eb/etc/bcheckrc / etc/bcheckrc. Reboot the system.

9. The following information is displayed when the system boots: INIT:SINGLE USER MODE / etc/initscript: / bin/sulogin:not found.

Analysis: description / bin/sulogin file is missing. This file is a symbolic link file, if the source file is intact, it can be recovered from the source file.

Solution:

1. Start the system and enter multi-user mode (the missing sulogin file cannot enter single-user mode).

two。 Run fsck to clean up the root file system.

3. Execute the command cp / opt/K/SCO/Unix/5.0.5Eb/bin/sulogin / bin/sulogin or ln-s / opt/K/SCO/Unix/5.0.5Eb/bin/sulogin / bin/sulogin. Reboot the system.

Display LOGIN:ERROR-Failed to initialize policy manager. (IFOR_PM_FATAL) when the system starts.

Analysis: the reason for the above errors is usually the wrong system time, which is earlier than the installation time of the operating system. It is generally due to the loss of BIOS parameters of the machine.

Solution:

Boot to enter the BIOS parameter setting, modify the time of the machine to the correct time. Or boot the operating system, enter single-user mode, and use the asktime or date command to modify the system at the correct time.

These are all the contents of the article "what are the common faults in Unix systems?" Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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