fatal daemon() failed: no such device

Exact error message:  nov 12 14:34:09   <hostname>  sshd2[15154]: fatal daemon() failed: no such device 



Steps to fix the error:

1.Remove /dev/null directory

   #rm -f /dev/null



2.create the special file for /dev/null 


 #mknod /dev/null c 1 3


This creates the /dev/null special file that is a special character file with the major device number 1 and the minor device  number 3.



3.Then start the sshd service


 # /etc/init.d/sshd start


 # /etc/init.d/sshd status



It will resolves the issue.

OS Installation steps for Dell Power Edge M620 Blade Server

OS Installation steps for Dell Power Edge M620 Blade Server

Steps:

1 . First assign an OA IP to the DELL chassis. then we can able to take it as remotely.

Open Browse, Login to that chassis, using assigned IP Address . 

2. By default, the Username is root, and password is calvin. enter these credentials.

3. Then we are able to login to Chassis. Here we can see Chassis have 16 Slots, But only 1 blade severs is presented.

Here we can see all the details of chassis.

4. Select particular Blade Sever.

5. Then Click on Launch Remote Console Button on the Quick Links tab. It will prompt you to the following page.

6. click on Launch Virtual console

7. Again click on Launch Remote Console. 

8. Now we are successfully able to login to particular Blade. Then we will see , how to Install OS on this Machine.

9. We can Install OS in Number of Ways, Here we will discuss OS installation through Image File.

10. Click on Add image, and Select a image file.  Click on Mount option. then Power Tab, Reboot the server.

11. While Booting Press F10 for life Cycle controller.

12. It will prompt you to Life Cycle Controller Screen.

 13. Select OS Deployment Option.

14. Select Deploy OS Option.

15. If  we want to configure Hard Ware RAID select Configure RAID First, other wise Select OS Deployment.

16, Select The Operating System from Listed Ones

17. Select Next option 

18. click on next button.

 19. Then Click On finish Button.

20. Then System will automatically rebooted.  

21. After this select Installation, it will ask you to enter Host name and IP, Gate way,Net mask  and DNS. enter all those things. with in 40 Min OS Installation will be finished. 

Slot 0 Drive Array controller controller failure issue on HP BL460c G7 servers

Slot 0 HP Smart array P44i0 controller controller issue?

Steps to resolve:

This error is mainly due to the HDD failure issue, But we have to find defective hard disk. In this case you find any amber color indication on Hard disk also.     

If you are observing this error on HP G7 blade servers, do the following steps to resolve this issue.

1. Remove 1 HDD from slot 0 on the Blade, and try to boot with another HDD. 

2. If you are observing any error like, there is no hard disk presented in drive array  to install the OS,, then we come to know that , slot 0 hard disk failed. just remove that slot 0  hard disk and put a new hard disk in the same slot , and boot the servers again.

3. After booting , you can observe a message called, Array initialization,then it will ask you press F2 to re-enable the Drive.Press F2 it will re enabled that drive. 

4. Then go to RAID levels, just check both hard disks are detecting or not.

5. If the RAID is configured with RAID  0, Then Re install the OS.

6. If it is configured with RAID 1 , no need to install the OS, it will automatically boot from Hard disk.

6. If your not observing any error message ,after 2nd step, then slot 1 hard disk was failed. then put  new hard disk in slot 1  and do the same.

How to create symbolic link in unix or linux?

To create a symbolic link in Unix or Linux, at the shell prompt, enter the following command:

surya# ln -s {target-filename} {symbolic-filename}

For example create softlink for /webroot/home/httpd/test.com/index.php as 

/home/surya/index.php,

enter the following command:

#ln -s /webroot/home/httpd/test.com/index.php /home/surya/index.php



How to check symbolic link is created or not?


#ls -l

lrwxrwxrwx 1 surya  surya    16 2012-09-24 16:53 index.php -> 
/webroot/home/httpd/test.com/index.php

How to find Software Raid levels using command in linux? or How to check The RAID level in linux?

How to find Software Raid levels using command prompt in linux? 
                      
                                   or 

How to check The RAID level in linux? 

surya # cat /proc/mdstat 

Personalities : [raid0] 

md0 : active raid0 sda8[0] sdb8[1]

      655355328 blocks 64k chunks


By using this command we can see Which RAID is configured on the Machine. 

But remember that this command wont work , If you are configuring Hard 

Ware RAID levels.

How to view system log messages in unix?

Q. where are the log files are  located under redhat or  Debian or Cento OS Linux server? How do I open or view log files? 

 Almost all log files are located under /var/log directory (and subdirectory). You can change to this directory using cd command. You can use less, more, cat or tail command to see the logs.  To Go to /var/logs directory:

# cd  /var/log/

# ls

To View common log file /var/log/messages using any one of the following command: 


# tail -f /var/log/messages, used in real time, it will show last 10 logs

# less /var/log/messages

# more /var/log/messages, we can see page page, press Tab to toggle between pages.

# vi /var/log/messages , to see in vi editor


# cat /var/log/messages


 Q. what is the use of log messages?

• logs are used to see the status of your system. which provides the error messages and services return messages
• with the help of logs we can trouble shoot the system erors

Linux Log files and usage

/var/log/dmesg  --> used for kernel boot messages

/var/log/messages  --> stores the standard system error messages

/var/log/maillog  --> mail system messages


/var/log/secure -->  security , authentication messages

/var/log/audit/audit.log -->  kernel auditing messages

var/log/debug -->Debugging log messages

 /var/log/faillog --> User failed login log file

/var/log/kern.log --> Kernel log file

 /var/log/lpr.log -->Printer log file

 /var/log/mail.* : All mail server message log files

 /var/log/mysql.* : MySQL server log file

 /var/log/user.log : All userlevel logs

 /var/log/xorg.0.log : X.org log file

/var/log/apache2/* : Apache web server log files directory

 /var/log/lighttpd/* : Lighttpd web server log files directory

/var/log/fsck/* : fsck command log

/var/log/apport.log : Application crash report 

Unix version using command

How to check Unix version using command prompt?

surya# cat /etc/*-release

SUSE Linux Enterprise Server 12 (x86_64)
VERSION = 12


surya# cat /proc/version 

Linux version 2.6.16.60-0.58.1.3835.0.PTF.638363-smp 

How to find out LAN card speed in linux ?

To Find full or half duplex speed:

You can use dmesg command to find out your duplex mode:


   # dmesg | grep -i duplex


O/P: 

eth0: link up, 1000Mbps, full-duplex, lpa 0x45E1


So we can come to know that it has 

1. One NIC card, i.e, etho.  if it has 2 NIC cards , it will show eth1 
2. It is 1000Mbps speed
3. Communication is full duplex mode.


Use ethtool to display or change ethernet card settings.  To display duplex speed.


# ethtool eth0

Output:

Settings for eth0:
        Supported ports: [ TP ]
        Supported link modes:   10baseT/Half 10baseT/Full
                                          100baseT/Half 100baseT/Full
                                          1000baseT/Full
        Supports auto-negotiation: Yes
        Advertised link modes:  10baseT/Half   10baseT/Full
                                          100baseT/Half  100baseT/Full
                                          1000baseT/Full
        Advertised auto-negotiation: Yes
        Speed: 1000Mb/s
        Duplex: Full
        Port: Twisted Pair
        PHYAD: 0
        Transceiver: internal
        Auto-negotiation: on
        Supports Wake-on: umbg
        Wake-on: g
        Current message level: 0x00000007 (7)
        Link detected: yes

Explanation:

So we come to know that , eth0 supports 10baseT/Half, 10baseT/Full, 100baseT/Half, 100baseT/Full and  1000baseT/Full.

But the network configured as 1000Mbps , Full duplex mode.

We can also use mii-tool to find out your duplex mode.   Type following command at shell prompt:

# mii-tool 

Output:

 eth0: negotiated 100baseTx-FD flow-control, link ok


Remember:

100baseTx-FD: 100Mbps full duplex (FD)
100baseTx-HD: 100Mbps half duplex (HD)
10baseT-FD:     10Mbps full duplex (FD)
10baseT-HD:    10Mbps half duplex (HD)

Differences between Ext2,Ext3 and Ext4 file systems.

EXT2 :
1.Ext2 was the standard file system for linux until the introduction of ext3.

 
2.It was introduced with the 1.0 kernel in 1993.Ext2 is flexible,can handle file system up to 4 TB,and supports long filenames up to 1012 characters.

 
3.It has sparse super blocks feature which increase file system performance.In case any user processes fill up a file system,ext2 normally reserves about 5% of disk blocks for exclusive use by root so that root can easily recover from that situation.Now our rescue diskettes use ext2 instead of minix.
 

4. much Fater

EXT3 :

1. Ext3 (Extended 3 file system) provides all the features of ext2,and also features journaling and backward compatibility with ext2.
 

2.The backward compatibility enables you to still run kernals that are only ext2-aware with ext3 partitions.we can also use all of the ext2 file system tuning,repair and recovery tools with ext3 also you can upgrade an ext2 file system to an ext3 file system without losing any of your data.

3.Ext3’s journaling feature speeds up the amount of time it takes to bring the file system back to a sane state if it’s not been cleanly unmounted (that is,in the event of a power outage or a system crash). Under ext2,when a file system is uncleanly mounted ,the whole file system must be checked.This takes a long time on large file systems.
 

4. On an ext3 system ,the system keeps a record of uncommitted file transactions and applies only those transactions when the system is brought back up.So a complete system check is not required and the system will come back up much faster.
 

5. A cleanly unmounted ext3 file system can be mounted and used as an ext2 file system,this capability can come in handy if you need to revert back to an older kernel that is not aware of ext3.The kernel sees the ext3 filesystem as an ext2 file system. 

6. ext3 file system is slower compared with ext2.

Ext4 :
1. Ext4 is part of the Linux 2.6.28 kernel,Ext4 is the evolution of the most used Linux file system, Ext3.
 

2. In many ways, Ext4 is a deeper improvement over Ext3 than Ext3 was over Ext2. Ext3 was mostly about adding journaling to Ext2, but Ext4 modifies important data structures of the file system such as the ones destined to store the file data. The result is a filesystem with an improved design, better performance, reliability and features.
 

3. slower compared with ext2

Features of Ext4 file system :  

1. Compatibility
2. Bigger filesystem/file sizes
3. Subdirectory scalability
4. Extents
5. Multiblock allocation
6. Delayed allocation
7. Fast fsck
8. Journal checksumming
9. Online defragmentation
10. Inode-related features
11. Persistent preallocation
12. Barriers on by default

Advantages of RHEL6 over RHEL5

1.Ext4 file system is introduced.

Ext4 has many new advantages than Ext3 which is used in earlier versions of RHEL. Ext4 is comparatively faster and easy to manage. It supports supports up to 100TB with the addition of Scalable Filesystem Add-one.

2. xen is removed and kernel virtualization machine (KVM) is introduced.

      RHEL6 introduces the use of KVM (Kernel-based Virtual Machine) as its hypervisor. In the earlier releases Xen hypervisor was used. The main advantage of KVM is that a new kernel should not be installed like in Xen. It also supports the installation of many virtual operating systems like Windows, Linux, Solaris,etc. It is easy to manage.

3. neat command is removed.

4. portmap service is removed.

5. iscsi is introduced, which supports for SAN.

RHEL6 is released with improved and new networking features. It supports IPv6. It uses NFSv4 (Network File Transfer) for the sharing of files in the network rather than NFSv3. It also supports iSCSI (internet Small Computer System Interface) partitions. The network manager in RHEL6 supports Wi-Fi capabilities.

6. rpmbuild is available, which is used to create our own rpms.

7. File encyption is added.

8. palimpsest is available for disk management.

9. Virtual machine will run only on 64bit processors.

10. postfix service is recommended instead of sendmail service

11.Improved level of security
      
RHEL6 has advanced level of security. SELinux (Security Enhanced Linux) features are improved and a new set of SELinux rules has been added to provide security to virtual machines from hackers and attackers. This new feature is called SVirt.

Squid proxy server configuration

1.SQUID PROXY
    BASIC
    TRANSPARENT SQUID PROXY
    CHILD SQUID PROXY

WITHOUT SQUID:
==============
ISP
 |
 |-----|SWITCH(Normal)|-----|---PC
                                       |---PC1
                                       |---PC2



SQUID PROXY:
=========

use: To share the internet through out the network with filter

[ISP] (dhcp/static)
  |
  |
[eth0]
  |
______
|        |
|        |
|        |--->(cache saved in /var/spool/squid)
|        |     ........................
 --------    |
  |           |
  |           |.........................
[eth1]--------[SWITCH]--|---[_]-->...{www.google.com}
                                  |---[_]
                                  |---[_]
                                  |---[_]

Profile: It is use for to share the internet throughout the network with filter

Package: squid, httpd

Port: 3128(default )

Demons:squid

script: /etc/init.d/squid

Configuration file: /etc/squid/squid.conf
 

Related: ACL

Service type: system-V-manage service

To configure squid we Required:

-->PC with 2 NIC cards names eth0 and eth1
-->ISP (internet public IP address) dhcp/static 51.73.171.26 provide to eth0

check 3128 port is open or not

#netstat -ntlp | grep 3128

RULES in squid server
    1. allow the network (eg: src )
    2. Deny the website (eg: dstdomain)
    3. Deny the Bad Words (eg: url_regex)
    4. Time resoritation (eg: time)
    5. password Auth for MD (eg: proxy_Auth)


STEPS to configure the SQUID PROXY:
========================

step 1. install squid ,http packages

#yum install squid* http* -y

step 2.Restart and enable services

#service squid restart
#service httpd restart
#chkconfig squid on
#chkconfig httpd on

3.To allow the Network
  ==============

  go to squid configuration file, i.e,

  #vim /etc/squid/squid.conf

  1.search for word "http_port" it is the squid listens port 3128 defalt( use   /http_port to search)

  2.search for word "INSERT" add below line

    acl mynet<rulename> src(keyword> 192.168.0.0/24

    http_access allow mynet

    save and exit

  3. restart service

     #service squid restart


4.To deny website
============

#vim /etc/squid/squid

#INSERT your own RULES: 

                              
acl mynet src 192.168.0.0/24
acl password proxy_auth REQUIRED
acl badsites dstdomain www.yahoo.com
acl badtime time 10:00-16:00 #(10am to 4pm)
acl badwords url_regex -i "/etc/badwords" #(create file /etc/badwords and write all bad words)
http_access deny badwords badtime
http_access deny badsites
http_access allow password
http_access allow mynet


To allowing users in bad time:===================

1.install a package htpasswd

#yum install http* -y
2. To allow user called bob

#htpasswd -mc /usr/etc/passwd bob

3. search for word called ncsa and write the following

auth_param basic program /usr/lib/squid/ncsa_auth /usr/etc/passwd
 

******************************************************


SQUID TRANSPARENT CONFIGURATION:=========================

Please follow these steps you will configure the squid with

#vim /etc/sysctl.conf

net.ipv4.ip_forward = 1

save & quit

#vim /etc/squid/squid.conf


##--please enable this options--##


http_port 3128 transparent

acl our_network src 192.168.1.0/24

http_access allow our_network

cache_mem 16M

access_log /var/log/squid/access.log

cache_log /var/log/squid/cache.log

store_log /var/log/squid/store.log

cache_dir /var/spool/squid 200016 256

cache_mgr user@desktop7.example.com

visible_hostname desktop7.example.com


save and quit

#squid -z

#service squid restart


#then if u want to make it transparent kindly add rules to iptable firewall##


#iptable -t nat -A PREROUTING -p tcp -i eth0 --dport 80 -j REDIRECT --to-port 3128


##If you would like to redirect the all http traffic through the proxy without needing to setup a proxy manually in all your applications you will need to add some rules,,


#ipables  -t nat -A PREROUTING -i eth1 -p tcp -m tcp --dport 80 -j DNAT --to-destination 192.168.0.1:3128


#####......Note: eth0 is connected with your LAN switch.......##





CHILD PROXY CONFIGURATION:==========================

_________
|             |
|             |MAIN PROXY SERVER
|             |192.168.0.254
|             |
|             |
|             |
-------------



            __________
            |               |
            |               |CHILD PROXY SERVER
            |               |
            |               |
            |               |
            |               |
            --------------

#vim /etc/squid/squid.conf

##search word for cache_peer
##uncomment following line

        hostname     type   Proxy icp port  options
cache_peer 192.168.0.254 parent 3128   3130     default

#service squid restart

Linux System Admin Interview Questions & Answers part 4

1.  What is the default UID when we are creating first user.(useradd)?
A: The first user created by root will always have a UID 500.
User ID=uid. The uid of root is 0.
UID from 1 to 499 is reserved for system services such as tha user apache,nagios,etc.

2. How many users are created by default.
A: Maximum users=60,000 by default.This could be increased.

3. Fields in password and shadow file.
A: Passwd file
Root:x:0:0:0:root:/root:/bin/bash
(username: encrypted form of password: uid: gid: personal info: home dir:shell)

4. When user is created which are the files it is updated.
A: /etc/passwd – contains various pieces of information for each user account
/etc/shadow – contains the encrypted password information for user’s accounts and optional the password aging information.
/etc/gshadow – group shadow file (contains the encrypted password for group)
/home –All users data is stored here.
/etc/login.defs---Shadow password suite configuration.

5. What is the owner of /tmp (is sticky bit applied on it)
A: drwxrwxrwt  11  root 20480 Apr 21 23:27 tmp (yes).

6. How to check which kernel module is installed?
A: modinfo-c
Also you can lok for the modules at:
Code:
/lib/modules
#rpm –qa  | grep ^kernel
#uname –r
#uname –rsv

7. What are modules,advantages and disadvantages of modules.
A: Modules are non-linked drivers.
Use of modules
Allow third party commercial development of drivers
Minimise kernel size
Allow smaller generic kernels
What is a Module
Contains device specific system routines
Fills in non-boot gaps in the kernel
Can be loaded and removed dynamically
Modules In Linux
Modules are compiled per Linux release
Multiple modules live in
/lib/modules/<kernel version>/
Hence only the active version modules will load
Accept parameters.

15. How to check which disk is fault in hardware Raid level
A: # watch cat/proc/mdstat       -    Check RAID status
#mdadm /dev/md1 –fail/add/remove /dev/sda6 - For RAID partition fail,add & remove

Linux System Admin Interview Questions & Answers part 3

1. Echo is used to Display message on screen. Which of the following options below should be used with echo to not output the trailing newline?
answer: -n

2. mount –r is used to mount a file in read only mode
answer: True

3. Which command is most useful when you want not only to send some data down a pipe, but also to save a copy?
Answer: tee

4. There is no difference between who and whoami command?
Correct answer: False

5. When trying to compare two files using cmp, if the files differ; what is the output?
answer: tells the first byte and line number where they differ

6. Cal is used to display calendar. If no arguments are supplied, what is displayed?
answer: The current month is displayed

7. Which of the following command is used to test a network connection?
answer: ping

8. Ping will only report damaged packets.
answer: False

9. Which of the following are valid functions of Red Hat Package Manager?
Answer: Used to verify software packages.search engine to search for software’s

10. What is the Non interactive mode of nslookup used for?
answer: Fetch information about the specified host or domain

11. Nettop is used to find network usage
Answer: True

12. In _____________ state of a process, the process will be terminated and the information will still be available in the process table.
Answer: Zombie

13. Which system call is used to bias the existing property of process?
answer: bias()

14. LD_LIBRARY_PATH is a type of
answer: Environmental variable

15. What is the major difference between UNIX and LINUX?
answer: Linux is an open source and free software

16. What is the use of a pipe?
Answer: Several functions can be combined in a single statement.Stream input to output.

17. By default, the shell uses the _______________ library
answer: readline

18. The kernel cannot be updated.
answer: False

19. Which of the following below are types of shell?
answer: sh, shell

20. The ______________ file contains all the information of users on your system
Answer: /etc/passwd

21. Which directory is used to write messages when kernel is loading? answer: /var/log/messages

22. Which command is used to report on the status of the quotas that have set including the amount of allocated space and amount of used space?
answer: repquota -a

23. Linux Supports Virtualized File Systems Like RAID.
answer: True

24. When Linux is installed, which account is created by default?
answer: Root

25. Using CHMOD if we want to give ALL permissions to a user, which mode is used?
answer: 777

26. Why do we use pgrep command?
answer: To search through the currently running processes

Linux System Admin Interview Questions & Answers part 2

1. Which of the following below are true functionalities of Kernel?
answer: Allocates time and memory to programs

2. Which of the following below are true functionalities of shell?
Answer: Authenticates user Interprets commands

3. Which command is used to find what is in your home directory?
Correct answer: % ls

4. cd home to get back to your home-directory?
answer: False

5. Which command is used to clear the screen?
Correct Answer: Clear

6. The head command writes the first _____________ lines of a file to the screen.
answer: ten

7. What is used to search files for specified words or patterns?
answer: grep

8. > symbol is used to redirect the output of a command
answer: True

9. Pipe symbol is represented by
answer: |

10. Which character is used to match exactly one character?
answer: ?

11. Which command is used to see the online manual?
answer: man

12. A process is identified by a unique
answer: pid

13. A process can run only in the background
Answer: True

14. Which command reduces the size of a file?
answer: gzip

15. Find command can search for?
nswer: Files


16. How can we find the current value for shell variables?
answer: Set command

17. What is the difference between PATH and path?
answer: PATH and path specify directories to search for commands and programs

Both variables always represent the same directory list
Altering either automatically causes the other to be changed

18. What is the default number of shell commands saved in the history list of .cshrc file?
Correct answer: 200

19. What is the difference between linux file system and windows file system?
answer: Under Windows, the various partitions are detected at boot and assigned a drive letter whereas Under Linux, unless you mount a partition or a device, the system does not know of the existence of that partition or device.

20. What is the content of /etc directory?
answer: it contains all configuration file

21. /temp is a type of filesystem directory
answer: False

22. The basic function of ______________ is to search files for lines (or other units of text) that contain a
answer: awk

23. Which of the following below is/are true for Date command?
answer: It can work w/o arguments

Linux System Admin Interview Questions & Answers part 1

1. Every command in Linux is a

1. Text file
2. Stored variable
3. Executable program

4. None

 Answer: executable program

2. How long can a filename in Linux be?
Correct answer: 255 characters

3. What is the shortcut key to go to home directory?

1. shift + cd
2. cd + enter key
3. alt + ctrl + cd

4. ctrl + cd

Correct answer: cd

4. The hierarchy of a series of directories branching in a user home directory starts from?

Correct answer: /home

5. Saving open files, flush the system cache and other necessary system maintenance are allowed by.

1. Restarting the system
2. Rebooting the system
3. Logging off the system

4. Shutting down the system

Correct answer: logging off the system

6. Which directory contains configuration files that stores system and application setting?

1      /etc
2      /lib
3      /usr

4      /var

Correct answer: /etc

7. Which command is used to find data files, programs, directories that match the search argument?
Correct answer: locate

8. Applications written to provide a GUI shell for UNIX and Linux are called
Correct answer: x window

9. The advantage of using SAMBA rather than NFS for file sharing in Linux is?
Correct answer: compatibility with Windows file sharing

10. Which framework is provided for the programs to interchange information about Linux OS?

1. Resource Sharing Framework

2. Resource Security Framework

3. Information Sharing Framework

4. Resource Definition Framework

Correct answer: Resource Definition Framework

11. To implement new application on IBM z/10. Which of the following options need to be considered if it to be implemented in Linux?
Correct answer: Red Hat Linux does not support all the devices supported by IBM z/OS

12. Which of the following has greater market share of Linux SW/HW environment?

1. Linux on z10
2. Linux HP integrity servers
3. Linux on AS/400 servers locate

4. Linux on DELL Xeon

Correct answer: Linux HP integrity servers

13. Which of the following commands can be run to remove all the rules in an iptables table?

1. iptables -L
2. iptables -A
3. iptables -F

4. iptables –delete

Correct answer: iptables -F (F=Flush)

14. Which of the following is the BEST way to set up SSH(Secure Shell) for communicating between Systems without needing passwords?

1. Use ssh-keygen for generating public-private keys.
2. Disable passwords on specific accounts that will use SSH.
3. Both A and B

4. None of the above

Correct answer: Use ssh-keygen for generating public-private keys.

15. How much usable space is available, when a Linux system is configured with a RAID 5 array that consists of six 20 GB hard disk drives?
Correct answer: 100 GB

Formula: S*(N-1)

            here S=size

            N=number of HDD.  remember it is only for RAID5

16. Which of the following commands can be used to check for file corruption?

1. md5sum
2. checkfile
3. cat -vet

4. tar –checksum

Correct answer: md5sum

17. Which of the following allows to secure remote command line access?
Correct answer: SSH(Secure Shell)

18. Which of the following supports for creating a Linux VPN (Virtual Private Network)?

1. RC2
2.3DES
3. chap

4. NTLMv2

Correct answer: 3DES

19. Which of the following commands delete the files from the /tmp directory, issued by non-root user?

1.mdir -rf /tmp/*
2.rm -rf /tmp/* -su
3.su -c "rm -rf /tmp/*"

4.su "rm -rf /tmp/*"

Correct answer: su -c "rm -rf /tmp/*"

20. Which configuration does cardmgr read at Linux system startup?

1      PCMCIA     cards
2      PCI   cards
3      USB  cards

4      SCSI cards

Correct answer: PCMCIA cards

21. When a computer system is reported problems with inodes and blocks, which of the following are the problem and its solution to rectify it?

1. The file system has become corrupt and needs to be repaired.
2. The boot sector is corrupt and needs to be repaired.
3. The drive is configured using an improper file system and needs to be reformatted.

4. The partition table has become corrupt and needs to be replaced.

Correct answer: The file system has become corrupt and needs to be repaired. Use fsck command

22. Which Linux command will successfully mounts a USB drive?

1. mount /dev/uda1 /mnt/usb
2. mount /dev/sda1 /mnt/usb
3. mount -t usbfs /dev/usb001 /mnt/usb

4. mount /dev/hde1 /mnt/usb

Correct answer: mount /dev/sda1 /mnt/usb

23. ___________ is a common tool for determining services and ports running on a remote Linux.

1. arp
2. nmap
3. netstat

4. None of the above

Correct answer: nmap

24. For supporting new diskless client workstations, which of the following services needs to be installed on a server?

1      dhcpcd      and   rexec               
2      named       and   httpd                
3      remoted     and   dhcpd                       

4      PXE   (Preboot    eXecution   Environment)      and   tftpd

Correct answer: PXE (Preboot eXecution Environment) and tftpd


25. Which of the following Linux commands could be used to find what processor was detected on boot, when a laptop system is slow/
Correct answer: POST

26 . How to accomplish the LILO boot configuration updation for supporting a newly installed IDE hard drive?
Correct answer: Edit lilo.conf and run "lilo -v -v"