1. How to read the arguments Hi, my name is (your name)\"passed to a shell scrip

Question

1. How to read the arguments Hi, my name is (your name)"passed to a shell script from the command line. Also, the script has to print the script name and the total number of arguments. 2. Write a shell script APP for a college that takes the input of student name, student ID, Five different courses. Finally, it has to print the average score and the grade of the student based on the following conditions: If the average>90: A grade If the average between 80 - 90: B grade If the average is between 70 - 80: C grade If the average is between 60 - 70: D grade If the average is less than 60: Fail 3. Write an APP for an A/V company called "Blue Bells". It has to display the list of Music albums or the Artist name. Based on the choice of selection, the main track name (song name) has to be displayed on the screen. Design the menu to store this information. (For example, in my APP if I enter Tobymac (Artist name) it would display "Lord, I need you" as it's a single song NOT an Album) 4. Write the shell script to input the electricity unit charge and calculate the total electricity bill according to the given condition: For first 50 units CAD 0.75/unit For next 100 units CAD 1.20/unit For next 100 units CAD 1.50/unit

Explanation / Answer

10)Answer:

Yum:

yum is the primary tool for getting, installing, deleting, querying, and managing Red Hat Enterprise Linux RPM software packages from official Red Hat software repositories, as well as other third-party repositories. yum is used in Red Hat Enterprise Linux versions 5 and later. Versions of Red Hat Enterprise Linux 4 and earlier used up2date

yum is an interactive, rpm based, package manager. It can automatically perform system updates, including dependency analysis and obsolete processing based on "repository" metadata. It can also perform installation of new packages, removal of old packages and perform queries on the installed and/or available packages among many other commands/services (see below). yum is similar to other high level package managers like apt-get and smart.

While there are some graphical interfaces directly to the yum code, more recent graphical interface development is happening with PackageKit and the gnome-packagekit application.

command is one of:
* install package1 [package2] [...]
* update [package1] [package2] [...]
* check-update
* upgrade [package1] [package2] [...]
* remove | erase package1 [package2] [...]
* list [...]
* info [...]
* provides | whatprovides feature1 [feature2] [...]
* clean [ packages | headers | metadata | dbcache | all ]
* makecache
* groupinstall group1 [group2] [...]
* groupupdate group1 [group2] [...]
* grouplist [hidden] [groupwildcard] [...]
* groupremove group1 [group2] [...]
* groupinfo group1 [...]
* search string1 [string2] [...]
* shell [filename]
* resolvedep dep1 [dep2] [...]
* localinstall rpmfile1 [rpmfile2] [...]
* localupdate rpmfile1 [rpmfile2] [...]
* reinstall package1 [package2] [...]
* downgrade package1 [package2] [...]
* deplist package1 [package2] [...]
* repolist [all|enabled|disabled]
* help [command]

Unless the --help or -h option is given, one of the above commands must be present.

Repository configuration is honored in all operations.

If the main obsoletes configure option is true (default) or the --obsoletes flag is present yum will include package obsoletes in its calculations - this makes it better for distro-version changes, for example: upgrading from somelinux 8.0 to somelinux 9.

GENERAL OPTIONS

Most command line options can be set using the configuration file as well and the descriptions indicate the necessary configuration option to set.

LIST OPTIONS

The following are the ways which you can invoke yum in list mode. Note that all list commands include information on the version of the package.

b)rpm:

RPM Package Manager (also known simply as RPM), originally called the Red-hat Package Manager, is a program for installing, uninstalling, and managing software packages in Linux. RPM was developed on the basis of the Linux Standard Base (LSB). In latter-day usage, the "RPM" portion of this term arises from the fact that .rpm is the default extension for files used by the program.

RPM Package Manager (RPM) (originally Red Hat Package Manager; now a recursive acronym) is a package management system.The name RPM refers to the following: the .rpm file format, files in the .rpm file format, software packaged in such files, and the package manager program itself. RPM was intended primarily for Linux distributions; the file format is the baseline package format of the Linux Standard Base.

Even though it was created for use in Red Hat Linux, RPM is now used in many Linux distributions. It has also been ported to some other operating systems, such as Novell NetWare (as of version 6.5 SP3), IBM's AIX (as of version 4), CentOS, Fedora (operating system) created jointly between Red Hat and the fedora community, and Oracle Linux. All versions or variants of the these linuxoperating systems use the RPM Package Manager.

An RPM package can contain an arbitrary set of files. The larger part of RPM files encountered are “binary RPMs” (or BRPMs) containing the compiled version of some software. There are also “source RPMs” (or SRPMs) files containing the source code used to produce a package. These have an appropriate tag in the file header that distinguishes them from normal (B)RPMs, causing them to be extracted to /usr/src on installation. SRPMs customarily carry the file extension “.src.rpm” (.spm on file systems limited to 3 extension characters, e.g. old DOS FAT).

There are five basic modes for RPM command

Advantages of RPM include straightforward program installation and uninstallation, automatic installation, ease of updating programs originally installed with RPM, and availability of versions for most distributions of Linux. Limitations that have been mentioned include lack of backward compatibility or inadequate documentation for certain programs, and a relatively steep learning curve.

c)du:

du command, short for disk usage, is used to estimate file space usage.
The du command can be used to track the files and directories which are consuming excessive amount of space on hard disk drive.

Syntax :

Examples :

Output:

0, –null : end each output line with NULL
-a, –all : write count of all files, not just directories
–apparent-size : print apparent sizes, rather than disk usage.
-B, –block-size=SIZE : scale sizes to SIZE before printing on console
-c, –total : produce grand total
-d, –max-depth=N : print total for directory only if it is N or fewer levels below command line argument
-h, –human-readable : print sizes in human readable format
-S, -separate-dirs : for directories, don’t include size of subdirectories
-s, –summarize : display only total for each directory
–time : show time of of last modification of any file or directory.
–exclude=PATTERN : exclude files that match PATTERN

Command usage examples with options :

Output:
This is partial output of above command.

Output:

Output:

Now try with level 2, you will get some extra directories

Output:

Output:

d)fstab:

fstab is a system configuration file on Linux and other Unix-like operating systems that contains information about major filesystems on the system. It takes its name from file systems table, and it is located in the /etc directory.

The term filesystem can refer to a hierarchy of directories (also called a directory tree) that is used to organize files on a computer system. It can also refer to the typeof filesystem, that is, how the storage of data is organized (i.e., files, folders, etc.) on a computer disk (hard disk, floppy disk, CDROM, etc.) or on a partition (i.e., a logically independent section) on a hard disk drive (HDD). Each type of filesystem has its own set of rules for controlling the allocation of disk space to files and for associating each file with its metadata (e.g., name, permissions and timestamps).

/etc/fstab is created automatically when the operating system is installed, and it is modified automatically when changes are made to the filesystems. It can also be modified by using specialized programs or manually by using a text editor.

The access permissions (i.e., the ability to read and modify) for /etc/fstab are set by default to read-only for ordinary users as a security and safety measure, and it is necessary to use the root (i.e., administrative) account to modify it. This is because even a small, unnoticed error could cause the system to malfunction, and repair could be difficult for ordinary users. When modifying configuration files such as /etc/fstab, it is important to make an emergency backup copy, preferable on a separate HDD or on removable storage media (e.g., a floppy disk), prior to opening it in a text editor.

/etc/fstab can be safely viewed by using the cat command (which is used to read text files) as follows:

cat /etc/fstab

It can be seen that the content of the file is a six-column table, with the columns separated by tabs or spaces. The columns are as follows:

(1) The first column lists the physical location of each filesystem, which can be a partition on the HDD or a separate device such as a CDROM or floppy disk. Partitions are generally listed in the order in which they are located on the HDD. If there are two HDDs, then all the partitions on the first one are listed first. Which drive is considered to be the first is defined in the computer's BIOS (basic input output system), which controls a computer's hardware while it is booting (i.e., starting up) and is usually stored in a flash memory chip. Also, filesystems that are mounted (i.e., logically attached to the system) beneath other filesystems must follow their parent partitions.

Any filesystem can be prevented from being automatically mounted during booting by commenting out the line on which it is listed. This is accomplished by using a text editor to add a hash symbol (#) to the beginning of the line. If at some later date it is decided to again let that filesystem be automatically mounted when the system boots up, all that is necessary is to remove the hash symbol.

(2) The second column shows the mount point, which is the directory in which the filesystem listed on that line is attached to the root filesystem (i.e., the main filesystem). Partitions that are located on removable storage media are usually mounted as a sub-directory of the directory /mnt, such as /mnt/floppy for floppy disks and /mnt/cdrom for CDROM drives. Some users may prefer to delete the /mnt directory and create directories for devices on the root partition, with names such as /floppy and /cdrom, in order to save time by typing in shorter mount commands. The mount command is used to manually mount filesystems and directories.

In general, no attempt should be made to modify lines containing the /proc directory. /proc is a filesystem that is used to gather information for commands such as psand pstree, which report on processes currently on the system. A process is a running instance of a program.

(3) The third column shows the filesystem type with which each partition or device is formatted. Most modern Linux distributions (i.e., versions) support a large number of filesystem types, among the most commonly used are ext2 (the basic Linux filesystem type), ext3 (an enhanced version of ext2 with journalingcapabilities), reiser (another journaling filesystem), vfat (which is compatible with some Microsoft filesystems), iso9660 (used by most CDROMs) and nfs (network file system). The entry swap shows that the partition is used as swap space (i.e., for virtual memory). The entry udf represents the Universal Disk Format) filesystem defined by the Optical Storage Technology Association, and is often used for CDROMs.

(4) The fourth column adds some basic security to the system by designating by whom and how the filesystem or device can be used. Numerous possible options are available, and any number of them can be used, provided that they are separated with commas and do not conflict with each other. Thus, the contents of this column for a partition or device can become rather long and extend into the space under other column headings.

The inclusion of the term user indicates that ordinary users are allowed to mount the filesystem; if user is replaced by nouser, it means that only the root user can mount the filesystem. owner means that the owner of the device is allowed to mount it. dev permits any user to mount the filesystem.

auto means that the the system tries to detect the filesystem type so that it can be mounted automatically when the computer is started or when the -a option (i.e., mount all filesystems mentioned in fstab) is used with the mount command. For auto to work, the kernel (i.e., the core of the operating system) must be compiled to support the type of filesystem to be mounted. noauto prevents the filesystem from being mounted when the computer starts, even when the -a option is used with the mount command; thus, a filesystem must be mounted manually (i.e., with the mount command) if it is to be used. ignore means that the system does not try to mount the partition or device; this is useful if it is desired to list all partitions on the system for later reference and possible mounting at some future date.

ro (read-only) allows users to read files on the filesystem but not modify them; rw (read-write) allows users to both read files on the filesystem and also write to them. exec lets users run executable files (i.e., programs) on the filesystem; no exec prevents users from running executable files on the filesystem.

suid permits user or group identifiers to be used on the partition. nosuid prevents user or group identifiers from being used. supermount, which is used in Mandriva Linux, allows floppies and CDROM disks to be replaced without the user having to unmount and remount them.

Red Hat and Fedora Linux include an option called kudzu for removable media drives, which allows such drives to be automatically added to and removed from /etc/fstab. This option can be deleted by the root user if it is desired to permanently add the entry for the corresponding removable media drive to /etc/fstab.

async indicates that all input and output to the filesystem or device should be performed asynchronously, and it is the default because of generally better performance. sync signifies that all input and output to the file system should be done synchronously.

defaults uses the default options, which are rw, suid, dev, exec, auto, nouser and async. If it is desired for all users to be able to use the partition or device freely, then this field should read: user, auto, dev, exec, rw.

(5) The fifth column is used to determine whether the dump command will back up the filesystem. This column is rarely used and has two options: 0, do not dump, which is used for most partitions, and 1, dump, which is used for the root partition.

(6) The sixth column is used by the fsck program to determine the order in which the computer checks the filesystems when it boots. The three possible values for the column are: 0, do not check, 1, check first (only the root partition should have this setting) and 2, check after the root partition has been checked. Most Linux distributions set all the partitions to 0, except for the root partition. If maintenance is important, 2 should be used, although this can increase the amount of time required for booting.

Because /etc/fstab defines how filesystems are mounted when starting the computer, changes made to the file will not take effect until the computer is restarted. It is read by the commands mount, umount (which unmounts filesystems), swapon (which which enables devices and files for swapping) and fsck, and thus it is important that all of its data be accurate and complete.

One of the nice features of /etc/fstab is that it will fill in the details for shortened mounting commands. For example, the command mount /mnt/cdrom can be used in place of the command mount -t iso9660 -ro,noauto,owner, /dev/cdrom /mnt/cdrom.

/etc/fstab does not necessarily list all potentially available partitions on the system, particularly if they are formatted for another operating system. The full list of partitions that are available for mounting can be seen by using the command fdisk as root and then typing the letter p and pressing the ENTER key. As the first HDD on a system is designated by hda, the following will list all available partitions on a system with a single HDD:

/sbin/fdisk /dev/hda

In contrast to the Microsoft Windows operating systems, in which partitions are labeled with letters, Linux gives each partition a three-part name. Partitions (as well as devices and ports) are defined in the /dev directory, thus each partition name starts with /dev. The first partition on a system is usually designated /dev/hda1. A partition that exists on another computer on the network usually consists of the name of the host (i.e., other computer on the network) followed by a colon, a space and a directory name

Filesystems that are described in /etc/fstab are typically mounted when the computer is booted, unless the noauto option is used. A list of which filesystems are actually mounted can be seen by using the mount command with no options and no arguments (i.e., input data), that is,

mount

Additional filesystems (i.e., those listed by fdisk) can be mounted immediately by using mount with the appropriate options and arguments. They can also be mounted at the next boot by modifying or adding entries to /etc/fstab.

e)fsck:

The system utility fsck (file system consistency check) is a tool for checking the consistency of a file system in Unix and Unix-like operating systems, such as Linux, macOS, and FreeBSD.

Linux fsck utility is used to check and repair Linux filesystems (ext2, ext3, ext4, etc.).

Depending on when was the last time a file system was checked, the system runs the fsck during boot time to check whether the filesystem is in consistent state. System administrator could also run it manually when there is a problem with the filesystems.

Make sure to execute the fsck on an unmounted file systems to avoid any data corruption issues.

This article explains 10 practical examples on how to execute fsck command to troubleshoot and fix any filesystem errors.

1. Filesystem Check on a Disk Partition

First, view all the available partitions on your system using parted command as shown below.

You can check a specific filesystem (for example: /dev/sda6) as shown below.

The following are the possible exit codes for fsck command.

2. Fsck Command Specific to a Filesystem Type

fsck internally uses the respective filesystem checker command for a filesystem check operation. These fsck checker commands are typically located under /sbin.

The following example show the various possible fsck checker commands (for example: fsck.ext2, fsck.ext3, fsck.ext4, etc.)

fsck command will give you an error when it doesn’t find a filesystem checker for the filesystem that is being checked.

For example, if you execute fsck over a ntfs partition, you’ll get the following error message. There is no fsck.ntfs under /sbin. So, this gives the following error message.

3. Check All Filesystems in One Run using Option -A

You can check all the filesystems in a single run of fsck using this option. This checks the file system in the order given by the fs_passno mentioned for each filesystem in /etc/fstab.

Please note that the filesystem with a fs_passno value of 0 are skipped, and greater than 0 are checked in the order.

The /etc/fstab contains the entries as listed below,

Here, the filesystem with the same fs_passno are checked in parallel in your system.

It is recommended that you exclude the root filesystem during this global check by adding -R option as shown below.

Note: Option -y is explained in one of the examples below.

4. Check Only a Specific Filesystem Type using Option -t

Using fsck -t option, you can specify the list of filesystem to be checked. When you are using with option -A, the fsck will check only the filesystem mentioned with this option -t. Note that fslist is a comma separated values.

Now, pass ext2 as the fslist value to -t option as shown below:

In this example, /dev/sda6 is the only partition created with the filesystem ext2, thus it get checked accordingly.

Using the keyword ‘no’ in front of filesystem, you can check all other filesystem types except a particular filesystem.

In the following example, ext2 filesystem is excluded from the check.

Tag Description install Is used to install the latest version of a package or group of packages while ensuring that all dependencies are satisfied. If no package matches the given package name(s), they are assumed to be a shell glob and any matches are then installed. If the name starts with an @ character the rest of the name is used as though passed to the groupinstall command. If the name is a file, then install works like localinstall. If the name doesn’t match a package, then package "provides" are searched (Eg. "_sqlitecache.so()(64bit)") as are filelists (Eg. "/usr/bin/yum"). Also note that for filelists, wildcards will match multiple packages. update If run without any packages, update will update every currently installed package. If one or more packages or package globs are specified, Yum will only update the listed packages. While updating packages, yum will ensure that all dependencies are satisfied. If the packages or globs specified match to packages which are not currently installed then update will not install them. update operates on groups, files, provides and filelists just like the "install" command.

If the main obsoletes configure option is true (default) or the --obsoletes flag is present yum will include package obsoletes in its calculations - this makes it better for distro-version changes, for example: upgrading from somelinux 8.0 to somelinux 9.

check-update Implemented so you could know if your machine had any updates that needed to be applied without running it interactively. Returns exit value of 100 if there are packages available for an update. Also returns a list of the pkgs to be updated in list format. Returns 0 if no packages are available for update. Returns 1 if an error occurred. Running in verbose mode also shows obsoletes. upgrade Is the same as the update command with the --obsoletes flag set. See update for more details. remove or erase Are used to remove the specified packages from the system as well as removing any packages which depend on the package being removed. remove operates on groups, files, provides and filelists just like the "install" command. list Is used to list various information about available packages; more complete details are available in the List Optionssection below. provides or whatprovides Is used to find out which package provides some feature or file. Just use a specific name or a file-glob-syntax wildcards to list the packages available or installed that provide that feature or file. search Is used to find any packages matching a string in the description, summary and package name fields of an rpm. Useful for finding a package you do not know by name but know by some word related to it. info Is used to list a description and summary information about available packages; takes the same arguments as in the List Options section below. clean Is used to clean up various things which accumulate in the yum cache directory over time. More complete details can be found in the Clean Options section below. makecache Is used to download and make usable all the metadata for the currently enabled yum repos. groupinstall Is used to install all of the individual packages in a group, of the specified types (this works as if you’d taken each of those package names and put them on the command line for a "yum install" command).
The group_package_types configuration option specifies which types will be installed. groupupdate Is just an alias for groupinstall, which will do the right thing because "yum install X" and "yum update X" do the same thing, when X is already installed. grouplist Is used to list the available groups from all yum repos. Groups are marked as "installed" if all mandatory packages are installed, or if a group doesn’t have any mandatory packages then it is installed if any of the optional or default package are installed. The optional "hidden" argument will also list groups marked as not being "user visible". If you pass the -v option, to enable verbose mode, then the groupid’s are displayed. groupremove Is used to remove all of the packages in a group, unlike "groupinstall" this will remove everything regardless of group_package_types. It is worth pointing out that packages can be in more than one group, so "groupinstall X Y" followed by "groupremove Y" does not do give you the same result as "groupinstall X". groupinfo Is used to give the description and package list of a group (and which type those packages are marked as). Note that you can use the yum-filter-data and yum-list-data plugins to get/use the data the other way around (Ie. what groups own packages need updating). If you pass the -v option, to enable verbose mode, then the package names are matched against installed/available packages similar to the list command. shell Is used to enter the ’yum shell’, when a filename is specified the contents of that file is executed in yum shell mode. See yum-shell(8) for more info resolvedep Is used to list packages providing the specified dependencies, at most one package is listed per dependency. localinstall Is used to install a set of local rpm files. If required the enabled repositories will be used to resolve dependencies. Note that the install command will do a local install, if given a filename. localupdate Is used to update the system by specifying local rpm files. Only the specified rpm files of which an older version is already installed will be installed, the remaining specified packages will be ignored. If required the enabled repositories will be used to resolve dependencies. Note that the update command will do a local install, if given a filename. reinstall Will reinstall the identically versioned package as is currently installed. This does not work for "installonly" packages, like Kernels. reinstall operates on groups, files, provides and filelists just like the "install" command. downgrade Will try and downgrade a package from the version currently installed to the previously highest version (or the specified version). The depsolver will not necessarily work, but if you specify all the packages it should work (and thus. all the simple cases will work). Also this does not work for "installonly" packages, like Kernels. downgrade operates on groups, files, provides and filelists just like the "install" command. deplist Produces a list of all dependencies and what packages provide those dependencies for the given packages. repolist Produces a list of configured repositories. The default is to list all enabled repositories. If you pass -v, for verbose mode, more information is listed. help Produces help, either for all commands or if given a command name then the help for that particular command.

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