Subject: Linux Administration Page: /
[QUESTIONS 1 TO 23]
Q1. What is active Directory?
Ans. Active Directory is the directory service used by Windows 2000. It is a core new
feature of the Windows 2000 operating system. The Active directory data store is the database in Active Directory that contains information about various types of network objects, including printer, shared folders, user accounts, groups and computers. In a Windows 2000 domain, a read/write copy of the Active Directory data store is physically located on each domain controller in the domain. The Active Directory data store is also called the directory.
Q2. Give any two major differences between Linux and windows 2000?
Ans. Sr. No Windows 2000 Linux
1. Windows is Licensed OS & developed by Microsoft. Where as Linux is open source, free under GNU and has many distributors such as red hat, mandrake, Suse etc.
2. Windows is less secure than Linux in case of virus, worms Where as Linux is more secure from this side.
Q3. Why there is need to create boot disk before installation of Linux?
Ans. We create boot disk before installation of linux because, if our installed boot loader is failed to access the boot loader from the hard disk then we can recover it with the help of this floppy. Because this file contain the LILO information file. Just insert bootable floppy disk into the floppy drive and press enter. This file will locate the Linux mount point and boot the system.
Q4. Give any two major differences between KDE and GNOME.
Ans. KDE is a desktop environment (the K Desktop Environment). KDE provides a set of libraries that allow an application to take advantage of some of the special features that the window manager has to offer. This includes things like drag-and-drop support, standardized printing support and so on. Where as GNOME (GNU Network Object Model Environment) offers a complete desktop environment and application framework to make development as well as usage easier. Like KDE, GNOME is not a window manager. GNOME provides development libraries and session management foundation features that we users don’t see.
Q5. What is difference between / and /root?
Ans. / is the root partition is for those core system files necessary to bring a system to single user mode. Once it is established, the partitions contents shouldn’t vary at all and definitely should not need to grow. Where as /root stand for root home directory. Where as the Linux administrator i.e. root will be known as /root directory.
Q6. List any two-boot manager for Linux.
Ans. The two Boot Manager;
1. LILO: - Linux loader, LILO does the same thing, which is done by the Windows NT boot loader NTLDR. It presents the menu at boot time and allowing you to select whether you want to run Linux or other OS.
2. GRUB: - Stand for Grand unified boot. This one is another boot manager for Linux. This boot manager handles the process of actually starting the load process of an operating system.
Q7. What is the use of LinuxConf?
Ans. LinuxConf is a powerful configuration tool, which is used for many different tasks. The main feature is its ability to create, delete, and modify users and groups.
Q8. List the different file system used by Linux.
Ans. Basically there are three type of file system used in Linux. They are ext2, ext3 or ReiserFS.
Ext2 :- An ext2 file system supports standard Unix file types (regular files, directories, symbolic links, etc). It provides the ability to assign long file names, up to 255 characters. Versions prior to Red Hat Linux 7.2 used ext2 file systems by default.
ext3 or ReiserFS: - The ext3 file system is based on the ext2 file system and has one main advantage of journaling. Using a journaling file system reduces time spent recovering a file system after a crash, as there is no need to fsck1 the file system. The ext3 file system will select by default and is highly recommended.
Q9. What are environments Variables?
Ans. In Linux System, every instance of shell has its own environment settings that give it a particular look, feel and behavior. These types of settings are typically controlled by environment variables.
Q10. What are the hardware requirements for installation of Linux?
Ans. Hardware Requirements
The following information represents the minimum hardware requirements necessary to successfully install Red Hat Linux 9:
CPU:
- Minimum: Pentium-class
- Recommended for text-mode: 200 MHz Pentium-class or better
- Recommended for graphical: 400 MHz Pentium II or better
Hard Disk Space (NOTE: Additional space will be required for user data):
- Custom Installation (minimum): 475MB
- Server (minimum): 850MB
- Personal Desktop: 1.7GB
- Workstation: 2.1GB
- Custom Installation (everything): 5.0GB
Memory:
- Minimum for text-mode: 64MB
- Minimum for graphical: 128MB
- Recommended for graphical: 192MB
Q11. What do you mean by File permission?
Ans. To enable the permission of read, write and execute on a particular user, file permission can be used. Permission is divided into four parts. The first part represented the first character of the permission. The 2nd, 3rd and 4th part of the permission represented in three characters. 1st part indicates the file owners, 2nd part indicates the group permission and the last part indicates the world permission.
Q12. What is PID Number?
Ans. PID stands for process identification number. All process should have their unique identification numbers and that number is known as PID.
Q13. Why there exists a file for each hardware device?
Ans. Because each hardware requires a file to work. Those files contain all the information about the existing hardware. The /dev/ is the name of the directory in which all device files reside. Since partitions reside on hard disks, and hard disks are devices, the files representing all possible partitions reside in /dev/.
Q14. List the command you can use to make your home directory as working directory.
Ans. Whenever we create a user it automatically create its home directory.
Q15. What are aliases?
Ans. The Alias setting allows directories to be outside the DocumentRoot directory and yet still accessible to the Web server. Any URL ending in the alias will automatically resolve to the alias' path. By default, one alias is already set up. The Web server can access an icons directory, but the directory is not in the DocumentRoot. The icons directory, an alias, is actually /var/www/icons/, not /var/www/html/icons/.
Q16. What are CUPS?
Ans. CUPS is the default print spooler, and redhat-config-printer is the recommended tool for configuring it. It may be launched from the System Settings menu, using the Printing menu entry. LPRng is still provided, and upgrades from previous installations using LPRng will continue to use it.
Q17. What is a man Command?
Ans. Man command stands for Manual. Manual pages are brief, yet complete, online documents that describe how to use specific command or system facility. It provides the help for linux commands.
Syntax for this command is as follows;
[root@ptu /root]man ls so the above command will display the manual pages for the ls command.
Q18. What is Quota Management in linux?
Ans. Linux has the facility of allocating user and group quotas. The edquota command helps the admin to edit these limits. There are two sorts of quota limits - a soft quota limit and a hard quota limit. When the soft quota limit is over ridded, the user receives an email saying that the quota has been overridden and the user has some 'grace period' to backup or delete files. Setting up quotas, is a very essential part of user management and it can help the administrator to architect very usable system policies.
Q19. What are shells?
Ans. In Linux, programs and commands are normally executed by a command interpreter. A command interpreter is a user process like any other process and that process is known as shell. There are many shells in Linux, some of the most popular are sh, bash and tcsh. With the exception of a few built in commands, such as cd and pwd, a command is an executable binary file. For each command entered, the shell searches the directories in the process's search path, held in the PATH environment
Q20. How a group is created?
Ans. The Group directive is similar to the User. The Group sets the group under which the server will answer requests. The default Group is apache. To create the group povide the following command on the shell prompt
[root@ptu /root]groupadd
Q21. What do you mean by /proc directory?
Ans. /proc:- A virtual file system containing information about system resources. More information about the meaning of the files in proc is obtained by entering the command man proc in a terminal window. The file proc.txt discusses the virtual file system in detail.
Q22. What is the purpose of top command?
Ans. The top command is an interactive version of ps. Instead of giving a static view of what is going on, top refreshes the screen with a list of processes every two to three seconds. From this list, you can reprioritize processes or kill them. The top program’s main disadvantage is that it’s a CPU hog. On a congested system, this program tends to complicate system management issues. Users start running top to see what’s going on, only to find several other people running the program as well, slowing down the system even more.
Q23. What is the GNU Public License?
Ans. The GNU project has been the GNU General Public License (GPL). This license explicitly states that the software being released is free, and that no one can ever take away these freedoms. It is acceptable to take the software and resell it, even for a profit; however, in this resale, the seller must release the full source code, including any changes. Because the resold package remains under the GPL, the package can be distributed free and resold yet again by anyone else for a profit.
Section – A 5 Marks Questions
Q1. What is difference between deleting and disabling a user account?
Ans. Deleting a user: - When we delete any existing user from the linux, it remove all entries from the /etc/passwd and /etc/shadow and references in the /etc/group file. These types of user cannot be revoked in future. To delete a user, we use the userdel command with the optional parameter. Forexample;
[Root@ptu /root]# userdel –r GP
Disabling User: - By disabling the user in linux, it keeps all the entries into /etc/passwd and /etc/shadow and references in the /etc/group file for invoking the user in future. When we disable a user account that account stop working for required time period. By enabling the account, it again comes in working mode.
Q2. What is the use of inetd and Xinetd processes? Explain it.
Ans. Inetd Process:- Inetd is daemon process. This is a special program that after starting, it release the control of the terminal from which they started. The role of inetd is as a superserver for other network server-related processes, like as telnet and ftp. Lots of services which are waiting for loading into the memory can be listed in inetd configuration file i.e. /etc/inetd.conf. The inetd handles the network code and pass incoming connection into process as its standard in and any of the process output is sent
back to the host that has connected to the process. The /etc/inetd.conf file is the configuration file which contain the structure of services.
Xinetd process:-is the newer version of inetd which comes along with linux red hat 7.0 The Xinetd program accomplish the same task as the regular inetd program, yet it includes a new configration file format and some additional features. Xinetd use a difrent format then inetd process. It means if you have application which relies on inetd process then we have to make some adjustment to make it work.
The /etc/xinetd.conf file consists a series of block that take the following format;
Blockname
{ variable = value }
Where blockname is the name of the block which can be defined and variable is the name of a variable within the context of the block and value is the value assigned o the variable.
Q3. What is Shell? What are their functions? How many different types of shell linux support?
Ans. A shell is a program that provides an interface to the system. Although the shell is less intuitive than common GUIs, most linux experts consider the shell to be much more powerful than GUIs. Because shells have been around for so long, many advanced features have been built into them. The shell is comparable to the window program Manager, except that the shell program used. By default linux supports BASH Shell i.e. Bourne Again Shell.
Function of Shell: -
1. Shell provides a way to run programs, work with file system, compile computer code, and manage the computer.
2. It is a command line interface containing a handful of built in commands.
3. It has the ability to launch other programs and control them.
4. A variety of shell exists with similar features but with different means.
Linux comes in several different shells which can be viewed in the /etc/shells file. Deciding which shell is right for your environment depends upon the program on which you are working.
The following shell are supported by Linux
1. sh or Bourne Shell: The original shell still used on UNIX systems and in UNIX related environments. This is the basic shell, a small program with few features. When in POSIXcompatible mode, bash will emulate this shell.
2. bash or Bourne Again Shell: The standard GNU shell, intuitive and flexible. Probably most advisable for beginning users while being at the same time a powerful tool for the advanced and professional user. On Linux, bash is the standard shell for common users. This shell is called the superset of the Bourne shell, a set of add-ons and plugins. This means that the Bourne Again Shell is compatible with the Bourne shell: commands that work in sh, also work in bash.
3. csh or C Shell: The syntax of this shell resembles that of the C programming language. Sometimes asked for by programmers.
4 tcsh or Turbo C Shell: A superset of the common C Shell, enhancing user friendliness and speed.
5. ksh or the Korn shell: Sometimes appreciated by people with a UNIX background. A superset of the Bourne shell, with standard configuration a nightmare for beginning users.
Q4. List out and explain briefly all the different steps involved in the boot process of Linux.
Ans. Booting steps of linux after the loading of LILO are given below.
1. Kernel loading: - Once Lilo has started, and we select the linux as operating system to boot, the very first thing that will be loaded is the kernel. In that time no other OS is running in the memory of PC and the PC have easy way to access all of their memory. So the kernel will be loaded into the first megabyte of available RAM. To accomplish it, the kernel is compressed. The head of the file contains the code necessary to bring the CPU into protected mode and decompress the reminder of the kernel.
2. Kernel executing: - When the kernel is loaded it start executing. It knows the function, which is built into it, that mean it can compile any part of the kernel. One the kernel has started a hardware probe, it determines what device drivers should be initialized. At this point the kernel can mount the root file system and start a program called init.
3. init Process: - This is the first non-kernel process that is started and it always gets the process ID number of 1. init reads its configuration file from /etc/inittab and determines the runlevel from where it should start. Each server has a specific purpose. The runlevel values are as follows.
Value Description
0 Halt the system
1 Enter single-user mode (no networking enabled)
2 Multiuser mode, but without NFS
3 Full Multiuser mode
4 Unused
5 Same as runlevel 3, except using an X Windows login rather than a text based login.
6 Reboot the system.
Q5. How Does Single-User mode differ from Multiuser-Mode?
Ans. The differences between single r and multi-user are as follows:
Q6. Explain the working of mount command with the help of suitable example.
Ans. In Linux every partitions are mounted so that they appear as subdirectory. The file system management process begins with the root directory. The partition containing the kernel and the core directory structure that is mounted at boot time. This single partition needs all the required utilities and configuration files to bring the system up to single user-mode. When the boot scripts are running then additional partitions are mounted and adding to the structure of the file system. The mount process overlays a single subdirectory with the directory tree of the partition it is trying to mount. When a new
directory is mounted, the mount process hides all the contents of previously mounted directory.
For example, /dev/hda1 is the root partition. It has the directory /usr which contain no files. The partition /dev/hda3 contain all the files that we want in /usr, so we mount /dev/hda3 to the directory /usr. Users can now simply change directories to /usr to see all the files from that partition.
Using the mount Command
The structure of the mount command is as follows;
[root@ptu /root]# Mount [options] device directory
Options for mount commands are
-a used for mount all file system listed in /etc/fstab.
-t fstype Specify the type of file system being mounted.
-o options Specifying options applying to this mount process.( like as ro, rw, exec etc.)
Q7. What are the basic functions of lpd daemon? How you can configure it? Explain by taking a suitable example.
Ans. The lpd (Line printer daemon) is a Linux way of handling printing requests. The model used by lpd is actually similar to the email process. The daemon listens for print request to come over the network. This mean that the daemon consider print request coming from other hosts to be just the same as those or originating from the same host as the daemon. When a print job arrives the file is at first place in a spool directory. This directory is /var/spool/lpd/printername, where printer name is the name of the printer to which the job is going. Once job is spooled, lpd gets the requested print job to the printer
independently of the sender.
The following are the steps for getting the job to the printer.
1. Look up the printer configuration information in /etc/printcap.
2. If the printer requires that the job go through a print filter, send it through filter.
3. If the printer is physically attached to the server, send the filtered request directly to the print device.
Configuring Printer
Download the latest version of LPRng from http://www.astart.com/lprng/LPRng.html and place it in that directory where you have enough space to unpack and compile the source Code.
Q8. Explain the file system supported by Linux?
Ans. Red Hat is committed to the File system Hierarchy Standard (FHS), a collaborative document that defines the names and locations of many _les and directories. We will continue to track and follow the standard to keep Red Hat Linux FHS-compliant. The current FHS document is the authoritative reference to any FHS-compliant file system, but the standard leaves many areas undefined or extensible.
1. FHS Organization:- The directories and files noted here are a small subset of those specified by the FHS document.
2. The /dev Directory:- The /dev directory contains file system entries which represent devices that are attached to the system. These files are essential for the system to function properly.
3. The /etc Directory:- The /etc directory is reserved for configuration files that are local to your machine. No binaries are to be put in /etc
4. The /lib Directory:- The /lib directory should contain only those libraries that are needed to execute the binaries in /bin and /sbin. These shared library images are particularly important for booting the system and executing commands within the root file system.
5. The /mnt Directory: - The /mnt directory is for temporarily mounted file systems, such as CDROMs and floppy disks.
6. The /opt Directory:- The /opt directory provides an area for large, static application software packages to be stored. For packages that wish to avoid putting their files throughout the file system, /opt provides a logical and predictable organizational system under that package's directory. This gives the system administrator an easy way to determine the role of each file within a particular package. For example, if sample is the name of a particular software package located within /opt, then all of its files could be placed within directories inside /opt/sample, such as /opt/sample/bin for binaries and /opt/sample/man for manual pages.
7. The /proc Directory - The /proc directory contains special "files" that either extract information from or send information to the kernel. Due to the great variety of data available within /proc and the many ways this directory can be used to communicate with the kernel.
8. The /sbin Directory:- The /sbin directory is for executables and used only by the root user. The executables in /sbin are only used to boot and mount /usr and perform system recovery operations.
9. The /usr Directory:- The /usr directory is for files that can be shared across a whole site. The /usr directory usually has its own partition, and it should be mountable read-only. The bin directory contains executables, dict contains non-FHS compliant documentation pages, etc. contains system-wide configuration files, games is for games, include contains C header files, kerberos contains binaries and much more for Kerberos, and lib contains object files and libraries that are not designed to be directly utilized by users or shell scripts.
10. The /usr/local Directory:- The /usr/local hierarchy is for use by the system administrator when installing software locally. It needs to be safe from being overwritten when the system software is updated. It may be used for programs and data that are shareable among a group of hosts, but not found in /usr. The /usr/local directory is similar in structure to the /usr directory.
11. The /var Directory:- The FHS requires that you should be able to mount /usr read-only, any programs that write log files or need spool or lock directories should write them to the /var directory. The FHS states /var is for: "...variable data files. This includes spool directories and files, administrative and logging data, and transient and temporary files.
12. /usr/local in Red Hat Linux:- In Red Hat Linux, the intended use for /usr/local is slightly different from that specified by the FHS. The FHS says that /usr/local should be place where you store software that is to remain safe from system software upgrades. Since system upgrades from Red Hat are done safely with the rpm command and graphical Package Management Tool application, you do not need to protect files by putting them in /usr/local. Instead, we recommend you to use /usr/local for software that is local to your machine.
Q9. Write down the steps of adding new Kernel to Boot.
Ans. The Linux kernel file (Vmlinuz-2.3.12) is placed in the /boot directory. The first step is to append the relevant information to the /etc/lilo.conf file. This will look like this;
Image=/boot/vmlinuz-2.3.12
label=linx-2.3.12
root=/dev/hda2
read-only
if we append this to the end of the /etc/lilo.conf then the vmlinuz-2.3.12 won’t become the default kernel that gets booted. For this we have to enter a command default. The default command is not the part that block so we can insert it at the beginning of the file.
The /etc/lilo.conf file will look like this;
default = vmlinux-2.3.12
boot=/dev/had
prompt
timeout=50
image=/boot/vmlinuz-2.2.5-15
label=linux
root=/dev/hda2
read-only
other = /dev/hda1
label=dos
table=/dev/had
image=/boot/vmlinuz-2.3.12
label=linux2.3.12
root=/dev/hda2
read-only
Now save this file run and this file by giving the following command;
[root@redhat /boot] # lilo
Q10. What is the function of /proc/filesystems?
Ans. /proc/filesystems: - This file displays a list of the file system types currently supported by the kernel. Sample output from a generic kernel's /proc/filesystems file looks similar to this:
nodev rootfs
nodev bdev
nodev proc
nodev sockfs
nodev tmpfs
nodev shm
nodev pipefs
ext2
nodev ramfs
iso9660
nodev devpts
ext3
nodev autofs
nodev binfmt_misc
The first column signifies whether the file system is mounted on a block device. Those beginning with nodev are not mounted on a device. The second column lists the name of the file systems supported. The mount command cycles through these file systems when one is not specified as an argument.
Q11. Discuss Following Command.
Ans. 1. chgrp:- This command line utility lets you to change the group setting of a file. It
Works much like chown.
E.g [root@ford /root]# chgrp [-r] groupname filename
2. mv:- The mv command is used to move files from one location to another. Files can be moved across partitions as well, that requires a copy operation to occur, so that move command may take longer. Some options of mv commands are
-f Forces move
-r Interactive move
e.g [root@ford /root]# mv /usr/src/myprog/bin/* /usr/bin
4. ln:- The ln command lets you establish hard links and soft links.
e.g [root@ford /root]# ln original file new file
5. find:- This command lets you search for files based on various criteria. find has a larger number of options that you can read about on its man page(manual page).
[root@ford /root]# find startdir [options]
where start_dir is the directory from which the search should start. To find all the files in /tmp directory that may have not been accessed in at last seven days.
[root@ford /root]# find /tmp –atime 7 –print
6. mkdir:- This command in linux is identical to the same command in other flavor of Unix as well as ms-dos. The only option available is –p, which will create parent directories if none, exists. [root@ford /root]# mkdir mydir
7. rmdir:- This command offers no surprise for those familiar with dos version of the command. It simply removes an existing directory. The only command-line parameter available for this is –p which removes parent directory as well.
[root@ford /root]# rmdir –p bigdir/subdir/mydir
or
[root@ford /root]# rmdir mydirpwd
8. pwd:- To get the present working directory
[root@ford /root]# pwd /usr/local/src
9. cat:- The cat program fills an extremely simple role: to display files. More creative things can be done with it, but nearly all of its usage will be in the form of simply displaying the contents of text files- much like type command under Dos.
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Section – A 2