PCBWay

1.What is Linux?

Answer: Linux is an operating system based on UNIX, and was first introduced by Linus Torvalds. It is based on the Linux Kernel, and can run on different hardware platforms manufactured by Intel, MIPS, HP, IBM, SPARC and Motorola. Another popular element in Linux is its mascot, a penguin figure named Tux.

2. What is the difference between UNIX and LINUX?

Answer :Unix originally began as a propriety operating system from Bell Laboratories, which later on spawned into different commercial versions. On the other hand, Linux is free, open source and intended as a non-propriety operating system for the masses.

3. Give me 15 commands which you use frequently.

Answer :Depends on the environment you work. Some examples are

mkdir – For creating folders( use -p option to create multiple folders at a time)

ls – List folders/files( check what ls -1 do)

top – To monitor system activities

To check whats happening on the server and which process open which file.

netstat -tcp –Gives you complete picture about network connection details.

vnstat –Gives you Network band width statics

sh –For running shell scripts

history –For monitoring the commands executed by users

cd –For changing directories

vi –-For editing configuration files.

chmod–To change permissions of folders and files.

Mount –For mounting formatted partitions.

service –For start/restart/stop a service.

chkconfig –For permanent on/off a service.

fdisk -l –To list all the partitions

This is my own list, you can have your list.

4. Give me some commands for user management.

Answer: last, chage, chsh, lsof, chown, chmod, useradd, userdel, newusers.

5. Give me syntax checking commands for following services

Answer: DNS, SAMBA, Apache etc

6. What is the command to do password less logins to other machines.

Answer: expect and ssh-keygen

7. Give me some security monitoring related commands.

Answer: lsof, netstat, top, ps -ef, tail, last, tcpdump, sestatus, history, w.

8. What is the difference between man, info, whatis commands and a –help option for a command?

Answer: man command gives you medium size info.

info command gives full details about a commands, lots and lots of information about a command. Please share your interview questions with us, we post them here so that others can get help from this.

9. What is Kerberos used for?

Answer: Kerberos is used for secure network logon.

10. Which partition store system configuration files in Linux system?

Answer: /etc partition stores system configuration files in Linux.

11. What is the purpose of the MD5 option on passwords?

Answer : MD5 is an encryption method that encrypts the password before saving.

Name any four general password rules for user account.

Answer:

  •  Include at least eight total characters
  • Use the string in an unrepeated way
  • Avoid use words that can be found in the dictionary
  •  Avoid use dates of significance, such as a birthday or anniversary A better method of password security is to create difficult-to-break passwords that are easy for the users to remember.

12. What is the alternative method to a GUI installation in Linux?

Answer : Linux provides text base installation as the alternative method of GUI installation.

13. What is the purpose of the swapon command?

Answer : swapon command is used to activate a already created swap partition. It cannot be used to create a new swap partition.

14. What is gzip?

Answer: gzip is a compression utility created by the GNU project.

15. What is tar?

Answer : tar is an archive utility that is used to create tape backups.

16. Which is the standard command used to uncompress gzip files?

Answer : The standard command used to uncompress gzip files is gunzip.

17. What is the RPM switch for only installing packages?

Answer : The command line switch for installing an RPM is -i.

18. What is the command used to install an RPM package named demofilename2.2- 2.i386.rpm?

Answer : The most common command used to install an RPM package is rpm -ivh. Following command will install the given package

#rpm -ivh demofilename2.2-2.i386.rpm

19. What is the command used to remove an RPM package named demofilename2.2- 2.i386.rpm?

Answer : The most common command used to remove an RPM package is rpm -evh. Following command will remove the given package

#rpm -evh demofilename2.2-2.i386.rpm

20. What is the command used to update an RPM package named demofilename2.2- 2.i386.rpm?

Answer : The most common command used to update an RPM package is rpm -Uvh. Following command will update the given package and remove the old.

#rpm -Uvh demofilename2.2-2.i386.rpm

21. PPP is most often used to create?

Answer: PPP is most often used to create serial point-to-point connections.

22. What fstab file do?

Answer : The fstab file is used to automatically mount file systems.

23. What inittab file do?

Answer : The /etc/inittab file is used to perform the default state and terminal connections for a Linux system.

24. What command can you use to verify the current active shell?

Answer : The env command will display the current active shell.

25. Where is the file. bashrc located?

Answer : The. bashrc file is usually located in the /home/username directory.

26. What function does the .bash_profile file perform?

Answer : The function of the .bash_profile file is to provide login initialization commands.

27. What function does the .bash_logout file perform?

Answer : The function of the .bash_logout is to provide logout functions

28. What function does the .bashrc file perform?

Answer : The function of the .bashrc file is to provide shell configuration commands.

29. What command would you use to shut down the system in 100 seconds?

Answer : #shutdown -h 100

30. What daemon controls the print spooling process?

Answer : The Line Printing Daemon (lpd) controls the print spooling process.

31. What configuration file defines the default runlevel for the init process?

Answer :/etc/inittab file defines the default runlevel for the init process.

32. Which command can you use to shut down and halt a Linux System?

Answer : The halt command will shut down a Linux system without rebooting

33. What init level should you set to bring the system to single-user mode?

Answer : init 1 will bring the system to single-user mode

34. A user wants to restart the NFS server because they want to enable changes made in the configuration file. What command accomplishes this task?

Answer : #service nfs reload

The reload command will tell the system to stop the service, reload the configuration file, and restart the service

35. What command can you use to reboot a Linux system?

Answer : The command to reboot a Linux system is reboot

36. What mode must you be in when using vi editor to input text into a file?

Answer : To insert text in the vi editor, you must be in insert mode

37. What is BASH?

Answer : BASH is short for Bourne Again SHell. It was written by Steve Bourne as a replacement to the original Bourne Shell (represented by /bin/sh). It combines all the features from the original version

of Bourne Shell, plus additional functions to make it easier and more convenient to use. It has since been adapted as the default shell for most systems running Linux.

38. What is Linux Kernel?

Answer : The Linux Kernel is a low-level systems software whose main role is to manage hardware resources for the user. It is also used to provide an interface for user-level interaction.

39. What is LILO?

Answer : LILO is a boot loader for Linux. It is used mainly to load the Linux operating system into main memory so that it can begin its operations.

40. What is a swap space?

Answer : A swap space is a certain amount of space used by Linux to temporarily hold some programs that are running concurrently. This happens when RAM does not have enough memory to hold all programs that are executing.

41. What is the advantage of open source?

Answer : Open source allows you to distribute your software, including source codes freely to anyone who is interested. People would then be able to add features and even debug and correct errors that are in the source code. They can even make it run better, and then redistribute these enhanced source code freely again. This eventually benefits everyone in the community.

42. What are the basic components of Linux?

Answer : Just like any other typical operating system, Linux has all of these components: kernel, shells and GUIs, system utilities, and application program. What makes Linux advantageous over other operating system is that every aspect comes with additional features and all codes for these are downloadable for free.

43. Does it help for a Linux system to have multiple desktop environments installed?

Answer : In general, one desktop environment, like KDE or Gnome, is good enough to operate without issues. It’s all a matter of preference for the user, although the system allows switching from one environment to another. Some programs will work on one environment and not work on the other, so it could also be considered a factor in selecting which environment to use.

44. A newbie enabled the root session for FTP server. is it ok?

Answer : No, he has put the security of entire server on risk. You should disable to root session as soon as possible.

45. A user complains you that he is unable to set ‘123’ as his password. Why would not the system allow this password?

Answer : There would be a minimum length rule for password, which is blocking user to use this password. Default minimum length rule for password is six characters. It means a user cannot have password less than six characters.

46. Your company is running Web Server. One dedicate account holder customer complains that his visitors are able to scan the directory tree. Which directive would you configure to stop web server from listing the directory?

Answer : You should remove/ comment the “Options Indexes” directive from the main configuration file ‘ httpd.conf’ of the web server. This is a security measure so that remote users can’t scan the directory tree of the server looking for security holes. Server won’t show directory listings if requested by a user.

47.What type of backup strategy can you use to fully back up a system every night?

Answer : You can use full backup strategy that will always perform a full backup of all files. This takes much more time and space than other methods, but is it the most complete method and allows for easy file restoration.

48. How can you enhance the security of password file?

Answer : Linux keep user account information in a text file called /etc/passwd. This file also store one way encrypted password. This file is accessed by several tools to get user information, so file need to world readable. This is a security risk. To minimize the security risk you can use shadow password format. This method save account information in regular file /etc/passwd. However, the password is stored as a single “x” character (not actually stored in this file). A second file, called “/etc/shadow”, contains encrypted password as well as other information such as account or password expiration values, etc. The /etc/shadow file is readable only by the root account and is therefore less of a security risk

49. What command should be used to make a tar archive to a disk file system located in /mnt/backup?

Answer : The correct command is tar -cvf /mnt/backup. The /mnt/backup directory should be on another machine to be fully effective as a backup strategy.

50. You have just finished the installation of sever. This server is going to be use as file server. Default installation have send mail service running, while this server will never send any e-mails. How should you deal with send mail service?

Answer : You should disable the send mail service if server is not being used for mail purpose. Leaving them running can increase the chance of a security vulnerability being exploited, and unauthorized use of sendmail relay.

51. What command can you use to back up an entire file system most efficiently?

Answer : The easiest command to use to back up an entire file system is the dump command. Files can

be restored from a dump operation by using the restore command.

52. Which necessary steps should you take to enhance the security of server just after the initial installation?

Answer:

  • Kernel and packages should be upgraded to the latest versions.
  • Unnecessary services and daemons should be disable.
  • Enable and configure firewall
  • Set a complex password policy

53. While auditing user accounts, an administrator notices that one of the users has a blank password. What should he do to the account?

Answer : To prevent further use of the account, which is an immediate security risk, disable it and set a temporary password for the user for the next time they login.

54. Which backup strategy backs up all files that have changed since the last backup?

Answer : An incremental backup will only back up files that have changed since the last backup.

55. Your company has terminated a server administrator. What is first thing as an administrator should you do to enhance the security?

Answer : Because the server administrator knows the root password for the server, it should be changed immediately to prevent them from tampering with the system.

56. You are setting up an FTP server. Only company employees are allowed to use the FTP services. What should you configure on the FTP server to enhance security?

Answer : You should disable the anonymous FTP account, so that only users with a username and password can access the system.

57. What is the location of system configuration files that should be backed up on a regular basis?

Answer : The /etc directory contains most of the Linux system configuration files.

58. Which permission allows a user to run an executable with the permissions of the owner of that file?

Answer : The Set-User-ID is a special permission that allows a user to run an executable with the permissions of the owner of that file.

59. What command can you use to make a tape archive file of a /home directory, and send it to the /dev/tape device?

Answer : The correct command is tar -cvf /dev/tape /home.

The -xvf option is used to extract files from an archive.

60. Employees at your company are lazy in changing the password. As a system administrator what can you do to minimize the security risk?

Answer : You can setup a password policy which enforce user to change his password after a specific time periods.

61. Which program should you use to connect a system remotely?

Answer : You should always use SSH to connect a system remotely. SSH is a secure method that encrypts the entire session.

62. To save disk space, an administrator wants to backup files, and then remove them from the server permanently. What kind of backup operation is this?

Answer : An archive operation will take the files, back them up to a device, and then remove the files from the original server.

63. What does firewall do?

Answer : Firewall is a device or service which can be used to protect the network or system from other outside networks.

64. Due to power fluctuation, your system starts up from a powered off state. You receive a warning error stating that the machine was not shut down properly, and fsck will be run. What is the cause of this message?

Answer : If your hard drive file systems are not unmounted properly, the fsck utility will automatically run the next time the system is started to fix any inconsistencies before they are mounted again. If they are not fixed, the file system can quickly become corrupt.

65. A junior system administrator is trying to read through a large log file using the cat command. Because it is so large, the cat command scrolls the file right to the end without allowing the start of the file to be read. What command can he be used to more easily read the file?

Answer : He can use less command instead of using cat command, which allows him to scroll through the file.

66. When you try to boot a Linux system, you receive a message stating that it canot mount the /home partition because of errors. While debugging, you found that it occur due to data error. What can you do to fix the problem?

Answer : You can use fsck utility that enable you to recover from the errors.

67. During the bootup of a Linux system, there is no output on the monitor, the machine beeps, and then halts the boot-up process. What is the most likely cause of the problem?

Answer : If the system would not even get to the POST stage, the problem is most likely with the motherboard itself. You should count and compare the number of beeps to the BIOS manual in order to determine which specific component failed.

68. Which utility could you use to repair the corrupted file system?

Answer : You can use fsck to repair the corrupted file system.

69. What is the core of Linux Operating System?

  1.  Shell
  2.  Kernel
  3.  Command
  4.  Script
  5.  Terminal

Answer: 3. Kernel is the core of Linux Operating System. Shell is a command Line Interpreter, Command is user Instruction to Computer, Script is collection of commands stored in a file and Terminal is a command Line Interface

70. What Linus Torvalds Created?

  1.  Fedora
  2.  Slackware
  3.  Debian
  4.  Gentoo
  5.  Linux

Answer: Linux Torvalds created Linux, which is the kernel (heart) of all of the above Operating System and all other Linux Operating System.

71. Torvalds, Wrote most of the Linux Kernel in C++ programming Language, do you agree?

Answer: No! Linux Kernel contains 12,020,528 Lines of codes out of which 2,151,595 Lines are comments. So remaining 9,868,933 lines are codes and out of 9,868,933 Lines of codes 7,896,318 are written in C Programming Language.

The remaining Lines of code 1,972,615 is written in C++, Assembly, Perl, Shell Script, Python, Bash Script, HTML, awk, yacc, lex, sed, etc.

Note: The Number of Lines of codes varies on daily basis and an average of more than 3,509 lines are being added to Kernel.

72. Linux initially was developed for intel X86 architecture but has been ported to other hardware platform than any other Operating System. Do you agree?

Answer: Yes, I do agree. Linux was written for x86 machine, and has been ported to all kind of platform. Today’s more than 90% of supercomputers are using Linux. Linux made a very promising future in mobile phone, Tablets. In-fact we are surrounded by Linux in remote controls, space science, Research, Web, Desktop Computing. The list is endless.

73. Is it legal to edit Linux Kernel?

Answer: Yes, Kernel is released under General Public Licence (GPL), and anyone can edit Linux Kernel to the extent permitted under GPL. Linux Kernel comes under the category of Free and Open Source Software (FOSS).

74. What is the basic difference between UNIX and Linux Operating System.

Answer: Linux Operating System is Free and Open Source Software, the kernel of which is created by Linus Torvalds and community. Well you can not say UNIX Operating System doesn’t comes under the category of Free and Open Source Software, BSD, is a variant of UNIX which comes under the category of FOSS. Moreover Big companies like Apple, IBM, Oracle, HP, etc. are contributing to UNIX Kernel.

75. What is the difference between service and process?

Answer: A process is any piece of software that is running on a computer. For example, your anti-virus software runs in the background as a process, which was automatically started when the computer booted. Some processes start when your computer boots, others are started manually when needed. Some processes are services that publish methods to access them, so other programs can call them as needed. Printing services would be an example of a service type of process, where your email program can just call the print services process to say it wants to print, and the service does the actual work.

76. How to view crond status?If it’s show service is not found.

Answer: Service crond restart

77. My clients are getting services from servers but how to know which client is using which service. is there any files to keep information about these? Clients used ftp, nis, samba, apache, squid, nfs and mail services how to know how many users got service from server side with date, time and client system ip?

Answer :

Mail server – /var/log/mail/maillog [RedHat,centos]
ssh – /var/log/secure
Apache – /var/log/http/access.log
nfs – /var/lib/nfs/rmtab

78. How to FTP user access other directory except his own home directory?

Answer :

vim /etc/vsftpd/vsftpd.conf
Chroot_list_enable=yes

79. What are the Linux-based security tools?

Answer:

  • Selinux
  • Firewall
  • iptables
  • Tcp-wrappers

80. What are the basic elements of firewall?

Answer: A firewall should be able to filter packets (drop/pass them) based on certain rules specified by the user. The rules may be used to identify an incoming packet to the computer or outgoing packet from the computer, it can be based on target port number/ip add, traffic from a particular Network card etc…

The firewall rules can be in a tabular form (saved on the disk) from where the firewall software can read them and implement it. iptables firewall on Linux is a great example

81. What is a command to display top 10 users who are using huge space?

Answer: du -sh /home/* | sort -r | head -10

82. How do find all failed login attempts via ssh?

Answer: tail -f /var/log/secure | grep Failed

83. How do you configure Linux system as a router?

Answer:

vim /etc/sysctl.conf
net.ipv4.ip_forward=1
system-config-network
eth0 192.168.1.120 eth0:1 172.24.0.1
255.255.255.0 255.255.0.0
172.24.0.1 192.168.1.120

84. What is the UID and GID of root user? Can a normal user can change the ownership of a file? What is the command to change ownership of a file?

Answer: The root UID/GID is 0 (zero). Which is why he can able to intervene in all normal users files even though he don’t had permission. A normal user will don’t have the permission to change ownership of file. The command to change ownership is < chown user.user file >

85. What is the diff b/w ext2 and ext3?

Answer : Ext3 is a tiny bit slower than ext2 is, but it holds tremendous advantages. There is really only one difference between ext2 and ext3, and that is that ext3 uses a journal to prevent filesystem corruption in the case of an unclean shutdown (ie. before the filesystem is synced to disk). That makes ext3 a bit slower than ext2 since all metadata changes are written to the journal, and then flushed to disk, but on the other hand you don’t risk having the entire filesystem destroyed at power failure or if an unwitted person turns the computer off uncleanly. You don’t have to check the filesystem after an unclean shutdown either. Ext3 has three levels of journalling. Metadata (ie. internal filesystem structures) are always journalled, so that the filesystem itself is never corrupted. How ordinary data is written to the file system is controllable, though. The default option is the “ordered” mode, which causes file contents to be written to the filesystem before metadata is even committed to the journal. The highest reliable mode is called the “journal” mode, which causes file data to be committed to the journal before it is flushed to its final place, like the metadata. The least reliable mode, but rumoured to be the fastest, is called the “writeback” mode, which makes no promises at all regarding the consistency of file data. Only metadata is output reliably in writeback mode. So as for anything else, it’s mainly a matter of priority. If you don’t want ultimate speed, go with ext3. If you need the highest speed that is theoratically aquirable though, then go with ext2. For that to be effective you’ll probably need a really advanced hard drive controller, though.

86. As the system administrator you need to review Bob’s cronjobs. What command would you use?

Answer: crontab –lu Bob

87. What command is used to remove the password assigned to a group?

Answer: gpasswd –r groupname

88. What are the different RAID levels?

Answer:

  • RAID level 0
  • RAID level RAID level 1
  • RAID level 2
  • RAID level 3
  • RAID level 4
  • RAID level 5
  • RAID level 6
  • RAID level 10
  • RAID level 50

89. How do you create a swapfile?

Answer:

dd if=/dev/zero of=/swapfile bs=1024 count=200M
mkswap /swapfile
swapon /swapfile

90. What does nslookup do?

Answer: Nslookup is a program used to find information about internet Domain Name server. The two modes of nslookup are: Interactive and non-interactive. Using ‘interactive mode’ user can query the name servers for the information pertaining to hosts and domains.

Using ‘non-interactive mode’ the user can just print the name and requested information of a host.

91. What is Linux and why is it so popular?

Answer : Linux is an operating system that uses UNIX like Operating system.

Unix interview questions with answers

92. How we can configure data hard derive during redhat 9 installation.

Answer : Have the data driver on a floppy drive. At the start of installation, when u boot from the CD/DVD, on the prompt, write “dd”. It will ask for the driver floppy later on and will load the sata driver. Then you can configure/partition the drive using disk druid or fdisk.

93. What is LILO?

Answer: LILO is Linux Loader is a boot loader for Linux. It is used to load Linux into the memory and start the Operating system.

94. What is the difference between home directory and working directory?

Answer : Home directory is the default working directory when a user logs in. On the other hand, working directory is the user’s current directory.

95. What is the difference between internal and external commands?

Answer : Internal commands are commands that are already loaded in the system. They can be executed any time and are independent.

96. Explain the difference between a static library and a dynamic library.

Answer: Static libraries are loaded when the program is compiled and dynamically-linked libraries are loaded in while.

97. What is LD_LIBRARY_PATH?

Answer : LD_LIBRARY_PATH is an environment variable. It is used for debugging a new library or a non standard library.

98.What is the file server in Linux server?

Answer : File server is used for file sharing. It enables the processes required for sharing.

99. What is NFS? What is its purpose?

Answer : NFS is Network File system. It is a file system used for sharing of files over a network.

100. How do I send email with linux?

Answer : Email can be sent in Linux using the mail command.

101. Explain RPM (Red Hat Package Manager) features.

Answer : RPM is a package managing system (collection of tools to manage software packages).

102.What is Kernel? Explain the task it performs.

Answer : Kernel is used in UNIX like systems and is considered to be the heart of the operating system.

103. What is Linux Shell? What is Shell Script?

Answer : Linux shell is a user interface used for executing the commands. Shell is a program the user.

104. What are Pipes? Explain use of pipes.

Answer : A pipe is a chain of processes so that output of one process (stdout) is fed an input (stdin) to another.

105. What Stateless Linux server? What feature it offers?

Answer : A stateless Linux server is a centralized server in which no state exists on the single workstations.

106. What does nslookup do? Explain its two modes.

Answer : Nslookup is used to find details related to a Domain name server. Details like IP addresses of a machine, MX records.

107. What is Bash Shell?

Answer : Bash is a free shell for UNIX. It is the default shell for most UNIX systems. It has a combination of the C and Korn shell features.

108. Explain some Network-Monitoring Tools in Linux: ping, traceroute, tcpdump, ntop.

Answer : Network monitoring tools are used to monitor the network, systems present on the network, traffic etc.

109. What happens to your ipchains settings when you reboot a machine?

Answer: They cannot be automatically saved unless you do something like make an alias for the shutdown routine that ensures this happens. Settings for ipchains are lost during a reboot or shutdown and there is no “setting” to ensure they are automatically saved. Answers a, b, and c are completely incorrect. Answer e is incorrect, but you can save them by hand if you choose to.

110. Which package provides secure remote login sessions, such as secure telnet logins?

Answer: The ssh package allows you to configure secure telnet sessions and other remote logins. Answer a points to an invalid package. Answer c points to a valid package, but shadow handles passwords, not data encryption. Answers d and e point to firewalling packages, which regulate what passes in and out of a LAN, but do not handle data encryption.

111. Which package can you use to regulate which network traffic is allowed to enter a specific machine, but not on any other machines?

Answer: The tcp_wrappers package is used to regulate the TCP/IP network traffic coming in and out of a machine. Answers b and c both point to valid firewalling packages, but these packages are used for an entire LAN, not just one machine. Answer d points to the commun-ications protocol used to transmit data over the Internet. Answer e points to an invalid package.

112. What type of server is used to remotely assign IP addresses to machines during the installation process?

Answer: you can use a DHCP server to assign IP addresses to individual machines during the installation process. Answers a, b, d, and e list legitimate Linux servers, but these servers do not provide IP addresses. The SMB, or Samba, tool is used for file and print sharing across multi-OS networks. An NFS server is for file sharing across Linux net-works. FTP is a file storage server that allows people to browse and retrieve information by logging in to it, and HTTP is for the Web

113. Which partitioning tool is available in all distributions?

Answer: The fdisk partitioning tool is available in all Linux distributions. Answers a, c, and e all handle partitioning, but do not come with all distributions. Disk Druid is made by Red Hat and used in its distribution along with some derivatives. Partition Magic and System Commander are tools made by third-party companies. Answer d is not a tool, but a file system type. Specifically, FAT32 is the file system type used in Windows 98.

Which first-level segment of the file system contains a majority of system The /etc portion of the file system contains a number of system and daemon configuration files. Answers a, c, d, and e are valid first-level directories, but are incorrect. The /var directory contains items that change on a regular basis, such as log files and print and mail spool directories. The /bin directory contains system binaries, whereas the /sbin directory contains binaries that run with SUID privileges or as a specific user. The /lib directory contains system libraries, both shared and non-shared.

114. Which file do you edit to set partitions to mount at boot time?

Answer: The file /etc/fstab manages which partitions are automatically mounted onto the file system. Answers b and c refer to valid items, but they are not used to manage the file system. The file /etc/services maps networking services to the ports they utilize, and /etc/smb.conf is the configuration file for the Samba service. Answers d and e point to files that do not exist.

115. Which first-level segment of the file system contains a majority of system and server configuration files within its subdirectories?

Answer: The /etc portion of the file system contains a number of system and daemon configuration files. Answers a, c, d, and e are valid first-level directories, but are incorrect. The /var directory contains items that change on a regular basis, such as log files and print and mail spool directories. The /bin directory contains system binaries, whereas the /sbin directory contains binaries that run with SUID privileges or as a specific user. The /lib directory contains system libraries, both shared and non-shared.

116. Which file do you edit to set partitions to mount at boot time?

Answer: The file /etc/fstab manages which partitions are automatically mounted onto the file system. Answers b and c refer to valid items, but they are not used to manage the file system. The file /etc/services maps networking services to the ports they utilize, and /etc/smb.conf is the configuration file for the Samba service. Answers d and e point to files that do not exist.

117. Which shell do you assign to a POP3 mail-only account?

Answer: You assign a POP3 only account to the /bin/false shell. Answers b and c both point to the same shell, the bash shell. However, assigning this shell to a POP3 only user gives him or her login access, which is what you are trying to avoid. Answers d and e are both invalid options in a standard setup.

118. What command would you use to create an empty file without opening it to edit it?

Answer: You use the touch command to create an empty file without needing to open it. Answers a and e point to invalid commands, though either of these might actually be aliased to point to a real command. Answers b and c utilize editors, and so do not satisfy the requirements of the question. actually touch is used to change the timestamps of a file if its exits, otherwise a new file with current timestamps will be created

119. Which command do you use to change run levels?

Answer: The command used to change run levels is init. Answers a, c, and d point to invalid commands. Answer b is a valid command, but does not set the current run level. The run level command displays the current run level, and the one that was used directly before entering this one.

120. Which daemon controls the network service -> POP3 mail service?

Answer: The inetd superdaemon controls the POP3 mail service. The POP3 mail service runs through the superdaemon, not on its own. Answers c and e point to nonexistent, or at least nonstandard daemons. Answer d points to the Usenet news daemon.

121. Who owns the data dictionary?

Answer:

The SYS user owns the data dictionary. The SYS and SYSTEM users are created when the database is created.

122. What is difference between AT and CRON?

Answer: cron can be set only for a particular time but at is used to schedule and execute Contact Author Contact Author Cron command is used to schedule the task daily at the same time repeatedly ,”at” command is used to schedule the task only once i.e. to run only one time.

123. What is difference between user right and user permission?

Answer:

user rights: User rights is that user is authorized to used password. if his password/file/dir is expired he is not able to login

user permission: Permission is user is permitted to use file/directory. that is authentication if he is authentication for particular file or not. It might be true as per my suggestion.

124.How do check the status of VERITAS Cluster Server?

Answer: hastatus –sum

125. Which is the main config file for VCS and where it is located?

Answer: main.cf is the main configuration file for VCS and it is located in /etc/VRTSvcs/conf/config.

126. Which command you will use to check the syntax of the main.cf?

Answer: hacf -verify /etc/VRTSvcs/conf/config

127. How will you check the status of individual resources of VCS cluster?

Answer: hares –state

128. What is the service group in VCS?

Answer: Service group is made up of resources and their links which you normally requires to maintain the HA of application.

129. What is the use of halink command?

Answer: halink is used to link the dependencies of the resources

130. What is the difference between switchover and failover?

Answer: Switchover is an manual task where as failover is automatic. You can switchover service group from online cluster node to offline cluster node in case of power outage, hardware failure, schedule shutdown and reboot. But the failover will failover the service group to the other node when VCS heartbeat link down, damaged, broken because of some disaster or system hung.

131. What is the use of hagrp command?

Answer: hagrp is used for doing administrative actions on service groups like online, offline, switch etc.

132. How to switchover the service group in VCS?

Answer: hagrp -switch (service_group) -to (system_name)

133. What is the basic difference between BASH and DOS?

Answer : The key differences between the BASH and DOS console lies in 3 areas:

  •  BASH commands are case sensitive while DOS commands are not;
  •  under BASH,/ character is a directory separator and acts as an escape character. Under DOS,/ serves as a command argument delimiter and is the directory separator
  •  DOS follows a convention in naming files, which is 8 character file name followed by a dot and 3 character for the extension. BASH follows no such convention.

134. What is the importance of the GNU project?

Answer : This so-called Free software movement allows several advantages, such as the freedom to run programs for any purpose and freedom to study and modify a program to your needs. It also allows you to redistribute copies of a software to other people, as well as freedom to improve software and have it released to the public.

135. Describe the root account.

Answer : The root account is like a systems administrator account, and allows you full control of the system. Here you can create and maintain user accounts, assigning different permissions for each account. It is the default account every time you install Linux.

136. What is CLI?

Answer: CLI is short for Command Line Interface. This interface allows user to type declarative commands to instruct the computer to perform operations. CLI offers an advantage in that there is greater flexibility. However, other users who are already accustom with using GUI find it difficult to remember commands including attributes that come with it.

137. What is GUI?

Answer : GUI, or Graphical User Interface, makes use of images and icons that users click and manipulate as a way of communicating with the computer. Instead of having to remember and type commands, the use of graphical elements makes it easier to interact with the system, as well as adding more attraction through images, icons and colors.

138. How do you open a command prompt when issuing a command?

Answer : To open the default shell (which is where the command prompt can be found), press Ctrl-AltF1. This will provide a command line interface (CLI) from which you can run commands as needed.

139. How can you find out how much memory Linux is using?

Answer : From a command shell, use the “concatenate” command: cat /proc/meminfo for memory usage information. You should see a line starting something like: Mem: 64655360, etc. This is the total memory Linux thinks it has available to use.

140. What is typical size for a swap partition under a Linux system?

Answer : The preferred size for a swap partition is twice the amount of physical memory available on the system. If this is not possible, then the minimum size should be the same as the amount of memory installed.

141. Which daemon is responsible for tracking events on Linux system?

Answer : syslogd is responsible for tracking system information and save it to the desired log files. It provides two system utilities which provide system logging and kernel message trapping. Internet and UNIX domain sockets support enable this utility package to support both local and remote logging. Every logged message contains at least a time and a hostname field, normally a program name field, too. So to track these information this daemon is used. syslogd mainly reacts to the set of signals given by the user. These are the signals given to syslogd: SIGHUP: This lets syslogd perform a reinitialization. All open files are closed, the configuration file (default is /etc/syslog.conf) will be reread and the syslog facility is started again. SIGTERM: The syslogd will die. SIGINT, SIGQUIT: If debugging is enabled these are ignored, otherwise syslogd will die. SIGUSR1: Switch debugging on/off. This option can only be used if syslogd is started with the – d debug option. SIGCHLD: Wait for Childs if some were born, because of waiting messages.

142. Which daemon is used for scheduling of the commands?

Answer : The crontab command is used for scheduling of the commands to run at a later time.

SYNTAX
crontab [-u user] file
crontab [-u user] {-l | -r | -e}

Options
-l List – display the current crontab entries.
-r Remove the current crontab.
-e Edit the current crontab using the editor specified by the VISUAL or EDITOR environment variables.

When user exits from the editor, the modified crontab will be installed automatically. Each user can have their own crontab, and though these are files in /var, they are not intended to be edited directly. If the –u option is given than the crontab gives the name of the user whose crontab is to be tweaked. If it is given without this then it will display the crontab of the user who is executing the command.

143. How environment variable is set so that the file permission can be automatically set to the newly created files?

Answer: umask command is used to set file permission on newly created files automatically.

Syntax
umask [-p] [-S] [mode]

It is represented in octal numbers. We can simply use this command without arguments to see the current file permissions. To change the permissions, mode is given in the arguments. The default umask used for normal user is 0002. The default umask for the root user is 0022. For calculating the original values, the values shown by the umask must be subtracted by the default values. It is mainly used for masking of the file and directory permission. The /etc/profile script is where the umask command is usually set for all users. The –S option can be used to see the current default permissions displayed in the alpha symbolic format.

For example, umask 022 ensures that new files will have at most 755 permissions (777 NAND 022). The permissions can be calculated by taking the NAND of original value with the default values of files and directories.

144. We saw the mention on the Linux BIOS website about one million devices shipped with Linux BIOS. Could you tell us more about these devices?

Answer: Yes, these are internet terminals that were built in India, based on the [x86 system-on-chip] STPC chip, I am told; also, there evidently is a Turkish-built digital TV that runs Linux BIOS. I have also heard that there are routers and many other embedded devices running Linux BIOS. I think at this point that 1 million is a low number. I am in contact with other set-top box vendors that are talking about numbers in the 10s of millions for their products. These numbers actually make the OLPC numbers seem small, which is in it amazing.

145. Which daemon controls the network service -> POP3 mail service?

Answer: The intend super daemon controls the POP3 mail service. The POP3 mail service runs through the super daemon, not on its own. Answers c and e point to nonexistent, or at least nonstandard daemons. Answer d points to the Usenet news daemon.

146. Who owns the data dictionary?

Answer: The SYS user owns the data dictionary. The SYS and SYSTEM users are created when the database is created. The SYS user owns the data dictionary. The SYS and SYSTEM users are created when the database is created.

147. What is difference between AT and CRON?

Answer: Cron command is used to schedule the task daily at the same time repeatedly ,”at” command is used to schedule the task only once i.e. to run only one time.

148. What is difference between user right and user permission?

Answer:

user rights : user rights is that user is authorized to used password. if his password/file/dir is expired he is not able to login

user permission: permission is user is permitted to use file/directory. that is authentication if he is authentication for particular file or not. it might be true as per my suggestion.

149. What is the real mean of DHCP?

Answer: Dynamic addressing simplifies network administration because the s/w keeps track of IP addresses rather than requiring an administrator to manage the task. That means new computer can be added to the network without any risk of manually assigning unique IP address.

150. You are debugging a new application that is crashing. You want to watch the messages as they are being written to the log. What command should you use?

Answer: The tail command allows you to keep a log open and see each new message as it is written to the log.

151. Which of the following tasks cannot be accomplished with the touch command?

Answer: The touch command is usually used to modify either a file’s access or modification time. It can also be used to create a new file.

152. You want to copy the user’s home directories to a new location. Which of the following commands will accomplish this?

Answer: The -r option tells the cp command to recurs the directories. The -P option retains the original permissions.

153. You read an article that lists the following command: dd if=/dev/fd0 bs=512 of=/new What does this accomplish?

Answer: The dd command is a special copy command often used for floppy disks and tapes. The if= option specifies the source; the bs= is the block size; and the of= option is the output.

154. You attempt to delete a file called sales.mem using the rm command but the command fails. What could be the problem?

Answer: In order to delete a file, you must have write rights to the directory containing the file.

155. You want to search for sale and sales. What regular expression should you use?

Answer: Use the asterick (*) to match to zero or more characters. The ‘$’ matches to any one character so sale$ would not find sale.

156. You have a file named ‘kickoff’ and would like to find every line beginning with a number. Which of the following commands will accomplish this?

Answer: The command grep ^[0-9] kickoff will cause grep to search the file kickoff for any line beginning with a digit.

157. You want to know how many lines in the kickoff file contains ‘prize’. Which of the following commands will produce the desired results?

Answer: Using the -c option with the grep command will show the total number of lines containing the specified pattern rather than displaying the lines containing the pattern.

158. You want to verify which lines in the file kickoff contain ‘Bob’. Which of the following commands will accomplish this?

Answer: The -n option when used with sed prints only the lines containing the pattern. In this case, the pattern is ‘Bob’ and the file to be searched is kickoff.

159. You have a file called docs.Z but do not know what it is. What is the easiest way to look at the contents of the file?

Answer: The .Z extension indicates that this is a file that has been compressed using the compress utility. The zcat utility provides the ability to display the contents of a compressed file.

160. You want to make it possible for your users to mount floppy disks. What do you need to do?

Answer: If you add the user option to the line in the fstab file that defines how to mount your CD-ROM, then your users will be able to mount it. What is contained in the directory The /proc directory is a virtual file system that contains system information.

161.After copying a file to a floppy disk, what should you do before removing the disk?

Answer: If you do not unmount the floppy before removing it, the files on the floppy may become corrupted.

162. You have set quotas for all your users but half of your users are using more space than they have been allotted. Which of the following could be the problem?

Answer: Quotas are set on a partition by partition basis. If your users have home directories on different partitions, you will need to configure quotas for each partition.

163. What command should you use to check the number of files and disk space used and each user’s defined quotas?

Answer: The repquota command is used to get a report on the status of the quotas you have set including the amount of allocated space and amount of used space.

164. you have a large spreadsheet located in the /data directory that five different people need to be able to change. How can you enable each user to edit the spreadsheet from their individual home directories?

Answer: By creating a link to the file in each user’s home directory, each user is able to easily open and edit the spreadsheet. Also, any changes that are made are seen by all the users with access.

165. You have a file called sales data and create symbolic links to it in bob’s home directory. Bob calls you and says that his link no longer works. How can you fix the link?

Answer: Because the link in bob’s directory is a symbolic link, if the file sales data in the /data directory is deleted, the symbolic link will no longer work.

166. You have two files in two different directories with the same inode. What type of link is involved?

Answer: Hard links all have the same inode number, unlike symbolic links.

167. You need to locate a file called sales data that one of your user’s created in his home directory but you do not know which one. How could you use the find command to locate this file?

Answer: When using the find command to locate a file by name you must specify the starting place in the directory hierarchy and the -name option to specify the file to search for.

168. However, when Bob attempts to open the file he is unsuccessful. What command do you need to use to give Bob ownership of the file?

Answer: The chown command can be used by root to give ownership of a file to any user.

169. What is meant by sticky bit?

Answer: When the sticky bit is set on a world writable directory, only the owner can delete any file contained in that directory.

170.Your default umask is 002. What does this mean?

Answer: The digits of your umask represent owner, group and others in that order. The 0 gives read and write for files and the 2 gives read only for files.

171. Which of the following commands will replace all occurrences of the word rate with the word speed in the file racing?

Answer: When using sed to do a search and replace, its default action is to only replace the first occurrence in each line. Adding the ‘g’ makes sed replace all occurrences of the search term even when it occurs multiple times on the same line.

172. You have a tab delimited file called phonenos and want to change each tab to four spaces. What command can you use to accomplish this?

Answer: By default, expand converts tabs to eight spaces. Use the -t option to change this behavior.

173. You issue the command head *. What would the resulting output be?

Answer: If the number of lines to display is not specified, the first ten lines of the specified file are displayed. The asterick tells head to display the content of each file in the present working directory.

174. what text filter can you use to display a binary file in octal numbers?

Answer: The od text filter will dumpt the contents of a file and display it in 2-byte octal numbers.

175. What would be the result of the command paste -s dog cat?

Answer: The paste text filter usually joins two files separating the corresponding lines with a tab. The -s option, however, will cause paste to display the first file, dog, then a new line character, and then the file cat.

176. What is the file server in Linux server?

Answer : 1

File server is used for file sharing. It enables the processes required fro sharing. All the files can be stored at a centralized location. Linux uses Samba to view the files on the server. Files on this server are backed up on a regular basis. Rights can be also assigned for the files on a file server.

Answer 2

A file server is dedicated for persisting files in a location from which the networked systems can access. Certain access privileges can be set for files.

Linux has software named as ‘samba’ which allows the files to be shared, viewed and edited on any remote system which may has Windows 9 x/ME/2000/NT or Macintosh computer systems. These files on the file server are backed up from time to time. If a file is deleted inadvertently, the file can be recovered from the backup tape.

177. What is NFS? What is its purpose?

Answer 1

NFS is Network File system. It is a file system used for sharing of files over a network. Other resources like printers and storage devices can also be shared. This means that using NFS files can be accessed remotely. Nfs command in linux can be used to achieve this.

Purpose of NFS:

  •  NFS can be used for sharing of files remotely.
  •  Data can be stored on a single machine and still remain accessible to others over the network.
  •  Reduction of the number of removable media drives throughout the network since they can be shared.

Answer 2

NFS stands for Network File System. NFS is used to partition a disk on a remote machine disk. NFS allows a quick way of file sharing.

The unwanted people access potential is provided by NFS to access hard drive in a network. So that an unauthorized user can not access one’s email, delete the files. File services from windows can be accessed. In other words files from one operating system can be shared by another using NFS.

178. How do I send email with linux?

Answer 1

Email can be sent in Linux using the mail command.

Mail [options] [users]
Options include: -s for subject, -c for carbon copy, -b for blind carbon copy

E.g. mail user_name –s “hello”

Answer 2

Linux supports to work with sending mails using a set of commands called as mail commands. The command to send email is ‘mail’. The ‘mail’ command is used to send and receive emails.

Syntax:

mail [options] [users]
Options are: -s,-c,-b
Where –s for subject, -c for copy and –b for blind carbon copy

Ex: mail username –s “Reports are needed”

It prompts displays the subject as “Reports are needed”.

Similarly if –c and –b is given the mail will be sent to the corresponding recipients.

179. Explain RPM (Red Hat Package Manager) features.

Answer 1

RPM is a package managing system (collection of tools to manage software packages).

Features:

  •  RPM can verify software packages.
  •  RPM can be served as a powerful search engine to search for software’s.
  •  Components, software’s etc can be upgraded using RPM without having to reinstall them
  •  Installing, reinstalling can be done with ease using RPM
  •  During updates RPM handles configuration files carefully, so that the customization is not lost.

Answer 2

RPM is a powerful software management tool for installing, uninstalling, verifying, querying and updating software packages. RPM is a straight forward program to perform the above software management tasks. It is available with Fedora, Suse, CentOS, Mandriva Linux and other version of Linux.

180. What is Kernel? Explain the task it performs.

Answer 1

Kernel is used in UNIX like systems and is considered to be the heart of the operating system. It is responsible for communication between hardware and software components. It is primarily used for managing the systems resources as well.

Kernel Activities:

  •  The Kernel task manager allows tasks to run concurrently.
  •  Managing the computer resources: Kernel allows the other programs to run and use the resources. Resources include i/o devices, CPU, memory.
  •  Kernel is responsible for Process management. It allows multiple processes to run simultaneously allowing user to multitask.
  • Kernel has an access to the systems memory and allows the processes to access the memory when required.
  •  Processes may also need to access the devices attached to the system. Kernel assists the processes in doing so.
  •  For the processes to access and make use of these services, system calls are used.

Answer 2

Kernel is the component that is responsible for managing the resources of a computer system.

The tasks are:

  •  Provides the abstraction level for resources such as memory, processors, and I/O devices.
  • Performs inter process communication
  • Responds to system calls
  • Provides methods for synchronization and communication between processes.

181. What is Linux Shell? What is Shell Script?

Answer 1

Linux shell is a user interface used for executing the commands. Shell is a program the user uses for executing the commands. In UNIX, any program can be the users shell. Shell categories in Linux are: Bourne shell compatible, C shell compatible, nontraditional, and historical.

A shell script, as the name suggests, is a script written for the shell. Script here means a programming language used to control the application. The shell script allows different commands entered in the shell to be executed. Shell script is easy to debug, quicker as compared to writing big programs. However the execution speed is slow because it launches a new process for every shell command executed. Examples of commands are cp, cn, cd.

Answer 2

Linux shell is the user interface to communicate with Linux operating system. Shell interprets the user requests, executes them. Shell may use kernel to execute certain programs. Shell Script: A shell script is a program file in which certain Linux commands are placed to execute one after another. A shell script is a flat text file. Shell scripts are useful to accept inputs and provide output to the user. Everyday automation process can be simplified by a shell script.

182. What are Pipes? Explain use of pipes.

Answer 1

A pipe is a chain of processes so that output of one process (stdout) is fed an input (stdin) to another. UNIX shell has a special syntax for creation of pipelines. The commands are written in sequence separated by |. Different filters are used for Pipes like AWK, GREP.

e.g. sort file | lpr (sort the file and send it to printer)

Uses of Pipe

  •  Several powerful functions can be in a single statement
  •  Streams of processes can be redirected to user specified locations using >

Answer 2

Pipe is a symbol used to provide output of one command as input to another command. The output of the command to the left of the pipe is sent as input to the command to the right of the pipe. The symbol is |.

For example:

$cat apple.txt | wc

In the above example the output of apple.txt file will be sent as input for wc command which counts the no. of words in a file. The file for which the no. of words counts is the file apple.txt.

Pipes are useful to chain up several programs, so that multiple commands can execute at once without using a shell script.

183. Explain trap command, shift Command, getopts command of linux.

Answer 1

Trap command: controls the action to be taken by the shell when a signal is received.

Trap [OPTIONS] [[arg] signspec..]

Arg is the action to be taken or executed on receiving a signal specified in signspec.

e.g. trap “rm $FILE; exit”// exit (signal) and remove file (action)

Shift Command: Using shift command, command line arguments can be accessed. The command causes the positional parameters shift to the left. Shift [n] where n defaults to 1. It is useful when several parameters need to be tested.

Getopts command: this command is used to parse arguments passed. It examines the next command line argument and determines whether it is a valid option

Getopts {optstring} {variable1}. Here, optsring contains letters to be recognized if a letter is followed by a colon, an argument should be specified. E.g (whether the argument begins with a minus sign and is followed by any single letter contained inside options) If not, diagnostic messages are shown. It is usually executed inside a loop.

Answer 2

trap command is used to catch a signal that is sent to a process. An action is taken based on the signal by using the action which is defined in the trap command instead of taking the default effect on the process.

Example:

$trap “echo ‘interrupt signal received’ “ INT.

shift command is used to replace the parameters that were sent from command line. For example $shift will replace $1 by $2

getopts command is used for the purpose of parsing positional parameters.

184. What Stateless Linux server? What feature it offers?

Answer 1

A stateless Linux server is a centralized server in which no state exists on the single workstations. There may be scenarios when a state of a partilcuar system is meaningful (A snap shot is taken then) and the user wants all the other machines to be in that state. This is where the stateless Linux server comes into picture.

Features:

  •  It stores the prototypes of every machine
  •  It stores snapshots taken for those systems
  •  It stores home directories for those systems
  •  Uses LDAP containing information of all systems to assist in finding out which snapshot (of state) should be running on which system

 Answer 2

Stateless linux is a way how a system is to run and be managed. Being a stateless system, a system should be able to be replaced at any time with or without local storage media. In case of hard drive crash, the command resync can be used to a new drive. If server goes offline, a new virtual instance that is running the OS image off of the network storage.

185. What command can you use to review boot messages?

Answer : Dmesg

186. Difference between swap partition and swap file?

Answer : Swap partition is maintained as a separate partition. Same swap partition can be used for two OS within single machine.

Suppose if the system crashes, there is a chance to recover or it may not corrupt the partition. Less fragmented.Where as swap file takes very less space. We can increase the space very easily, compared to swap partition. Swap file system fragmented.

If the system crashes then there is a huge chance to lost the swap file system.

187. A file which is not deleted by normal user and also root (using rm), for that type of file how we delete it?

Answer : Using chattr command, we need to change the attributes and then we remove using rm command. Eg:

– chattr -iIu example

rm -rf example

188. Difference between nfs soft and hard mounting points?

Answer:

Hard mount option: – If the client fails to access the server, then the connection hangs and once the system is up then it will again access the server.

Soft: – If the client failed to connect the server, it immediately gives the error report and closes the connection.

189. If we transfer 100 files by ftp to remote server, how to know the files are successfully transfer or some file are not transferred?

Answer:

ftp>mput 1 2 3 …. 100
ftp> ls –l

190. I know ssh, telnet, dns,apache all are worked on TCP/UDP but i want to know any one service which are working on UDP only?

Answer:

snmptrap 162/udp
snmptrap – simple network management protocol trap
snmptrapd is an SNMP application that receives and logs

191. I want to built a fire wall using iptables. My condition is ” inbound to 192.168.0.2 with a port of 80 from 172.168.0.1 should accept”

Answer: iptables –A INPUT –p tcp –dport 80 –s 172.168.0.1 –d 192.168.0.2 –j ACCEPT

192. I want to see how many interfaces (Ethernet cards) are working using single command

Answer: ifconfig

193. What is the status code 403,404 represented in apache server?

Answer: 403 represent forbidden error, means if a file misses some selinux security context. 404 represent that there is a cgi script missing or web pages missing.

194. How to monitor ports in a linux machine, with single command?

Answer: nmap localhost

195. In my linux machine, i lost /etc/passwd file and /etc/shadow file, then how can i recover it?

Answer: Normally in linux we must have backup by default for /etc/passwd and /etc/shadow files
/etc/passwd —> /etc/passwd-
/etc/shadow —> /etc/shadow-

from there we can copy or restore. If both are not available. Then follow below steps:

1. reboot
2. Single user mode [single init=/bin/bash]
3. pwconv
4. check /etc/passwd and /etc/shadow files are there
5. sync
6. init 3 or reboot with init 3

196. what r the different command to check ram,process and hdd of linux machine

Answer:

To check ram in your system:
#free

To check process
#ps
#top

To check hdd
#fdisk
#sfdisk -l

197. If I run ls command it will show me the junk output what is problem and how to resolve it

Answer: Set your terminal setting by stty and before that, export ls command to PATH variable

198. WHAT IS THE MEANING OF AIX

Answer: AIX (Advanced Interactive eXecutive) is an open operating system from IBM which is based on a version of UNIX. AIX/ESA was designed for IBM’s System/390 or large server hardware platform. AIX/6000 is an operating system that runs on IBM’s workstation platform, the RISC System/6000.

199. Why ls -F dev/log file output indicate as = sign at end of the file name?

Answer : Standard output

200. What is nis server?

Answer : NIS is a service that provides any user on a network with the same working environment irrespective of the system on that network, which has been used for login purpose.

For example if NIS server is set up in a single system and configured to hold user accounts and their passwords and access information. Then any user on that network can login to his/her account from any system (with nis client running) on that configured network. This gives a look and feel that the user is logged into his/her own system. But actually it’s the account on the NIS server that is mounted on the local system user login.