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Right option is (b) all FILES in the DIRECTORY having a filename starting with dir

For EXPLANATION I would say: The above COMMAND displays those files in the directory, the NAMES of which will be starting with a prefix ‘dir’. Here * is a meta-character which is used for pattern matching.

Correct option is (a) last modification time

For explanation: ls-t displays the FILENAMES based on the value of the last modification time of the FILE i.e. it sorts all the filenames in ACCORDANCE with their last modification time.

The correct answer is (b) LAST access time

For explanation: ls-u DISPLAYS the FILENAMES BASED on the value of the last access time of the file i.e. it SORTS all the filenames according to their last access time.

Correct choice is (a) True

To elaborate: FILES are stored onto the disk in TERMS of BLOCK size. The block size allocated to the file can be displayed using -s OPTION with LS command.

The correct ANSWER is (c) sorts according to FILE size

Easiest EXPLANATION: ls -S sorts the FILENAMES according to the file size with largest size FIRST.

Correct option is (b) False

The best I can explain: Both -r and -R are different options and performs different TASKS. -r is used to sort the filenames in REVERSE order while sorting while -R is used for recursive LISTING of files.

Right ANSWER is (a) Numerals>Uppercase> Lowercase

Explanation: The OUTPUT of ls commad is arranged in ASCII collating SEQUENCE which is, filenames STARTING with Numerals first, then Uppercase, then lowercase.

The correct option is (a) USING -F option

Best explanation: The OUTPUT of the ls command simply DISPLAYS filenames without indicating the file type. For identifying the file type we USE -F option. The output of ls-F displays filenames with two symbols * and /, which are type indicators. The filenames containing * are executables while those containing / are directories.

Right CHOICE is (a) -x

Best explanation: If there are multiple FILES PRESENT in a DIRECTORY for listing, it is better that we display these files in multiple COLUMNS. For this purpose -x is used. For example,

Right option is (a) for showing hidden files

The best EXPLANATION: -a option when used with ls command displays all the files including hidden files. Files beginning with a ( . ) are listed using -a option. There are certain files (FILENAMES beginning with a. ) These files are not listed without -a option.

Correct option is (c) -d

For EXPLANATION: LS command when USED with directory name as an argument, lists all the files in the directory. To FORCE ls to list the attributes of the directory we use the -LD option.

The correct choice is (c) ls

Easiest EXPLANATION: ls command is one of the most powerful commands USED in UNIX system. It comes available with a BUNCH of options for listing files available in the directory. There are a number of options LIKE -l, -a which are used for listing files in different manners according to user’s need.

Right choice is (b) -l

Explanation: -l is used with ls command for long listing of files in ASCII collating sequence. The attributes DISPLAYED are:

-> File TYPE and permissions

-> Links

-> Ownership

-> Group ownership

-> File size

-> Last modification TIME

-> Filename

Correct OPTION is (d) /

To EXPLAIN I would say: For changing your directory to the PARENT of current directory we can use ( . . ) with cd COMMAND. If we want to move more than one level up then we can use the ( . . ) separated by / .

Correct answer is (a) True

Explanation: HOME is a shell VARIABLE which PRINTS our home directory. The pathname SPECIFIED by the output of HOME is an EXAMPLE of absolute pathname.

The CORRECT ANSWER is (b) False

The explanation is: WHENEVER the pathname is relative to the root it is an EXAMPLE of relative pathname. The above pathname is also relative to the root, so it is an example of relative pathname.

Right choice is (b) ONE

For EXPLANATION: ( . . ) two dots represent the parent DIRECTORY. So cd . . will make US move one LEVEL up. For example,

The CORRECT choice is (d) ( . ) and ( . . )

The explanation: Relative pathname uses TWO cryptic symbols which are ( . ) and ( . . )

(.)a single dot represent the current directory.

( . . ) two DOTS represent the parent directory.

Correct choice is (C) PATHNAME RELATIVE to parent and current DIRECTORY

To elaborate: When a file uses its parent or current directory as a reference for navigation, such a pathname is called absolute pathname.

Correct option is (b) pathname relative to the root (/)

To elaborate: When a FILE’s pathname is DETERMINED with RESPECT to the root(/), such a pathname is CALLED ABSOLUTE pathname. No two files in a UNIX system can have same absolute pathnames. Two files can be of same name but in different directories hence their pathname would be different from each other. For example, /bin/user06/dir_01is an example of absolute pathname.

Right option is (a) True

Best EXPLANATION: PATHNAME is basically a sequence of symbols and filenames which indicates the location of our FILE in the hierarchical file system. pathname is of two types – absolute and RELATIVE pathnames. For EXAMPLE,

Correct option is (b) False

Explanation: pwd is used for DISPLAYING the absolute pathname of our current WORKING dircectory while $HOME DISPLAYS the absolute pathname of our home directory.

Right choice is (d) dir001 doesn’t exist, dir001 is not empty and permissions of dir001 doesn’t allow to REMOVE it

To elaborate: There could be MULTIPLE reasons which could lead to FAILURE while removing a directory. Major reasons could be:

->directory doesn’t exists.

->directory is not empty.

->permissions of directory doesn’t allow to remove it.

The correct option is (a) True

For explanation I would say: For performing any OPERATION on the file system, the user must be HIERARCHICALLY above the directory or should be in PARENT directory of the directory on which the operation is to be performed. Without FOLLOWING this rule, the user will not be able to perform any operation on the file system.

Correct CHOICE is (a) True

The best explanation: Like MKDIR command, we can delete multiple directories using ONE shot of rmdir command. While deleting directories and subdirectories, a reverse LOGIC is applied i.e. first the subdirectories or the CHILD directories are removed and then their parent directories.

The correct answer is (b) RMDIR

The explanation is: rmdir command is used for removing directories provided the DIRECTORY should be empty. For example, to remove a directory named dir_001 in the current directory TYPE the following command on the TERMINAL.

Right ANSWER is (d) the directory may exist, there may be an ordinary file, the permissions set for the CURRENT directory does not allow the creation

The best I can explain: Sometimes we are not able to create directory because of multiple reasons as STATED above.

The correct option is (a) True

Explanation: Multiple directories can be CREATED by ONE MKDIR COMMAND.

Right choice is (B) mkdir

To explain: DIRECTORIES in UNIX are created using mkdir command. The NAME of the directory to be created is specified as an ARGUMENT to the mkdir command. For example, to create a dir named dir_01 in the current directory we can use the FOLLOWING command,

The correct answer is (a) cd

For explanation I would say: cd (change directory) command is used for moving around the file SYSTEM. cd command is usually invoked with a argument. After INVOCATION, it changes the CURRENT directory to the directory SPECIFIED as argument. Cp command is used for copying files while rm command is used for deleting files.

For example: our current directory is /bin/user06 and we want to change our directory to a directory named dir_one which is inside the user06 directory. To do so, TYPE the following:

Right choice is (a) /, NULL

The best I can explain: UNIX imposes no rules in framing FILENAME extensions but there are some SPECIAL characters which cannot be used while naming a file. / and NULL are the characters which cannot be used in a filename.

The CORRECT choice is (b) False

The explanation is: Since UNIX is sensitive to case, filenames are also. HENCE, chap01, Chap01 and CHAP01 are three different files and can exist in the same directory.

Right answer is (a) True

The BEST explanation: UNIX imposes no RULES for framing filename extensions. For example, a shell script doesn’t need to have the .sh implication, even though it helps in identification. In all cases, it’s the application that imposes the restriction. For example, C COMPILER EXPECTS C PROGRAM filenames to end with .c .

Right answer is (b) /

For EXPLANATION I WOULD say: The root directory (/)serves as a reference point for all the files. All the files are HIERARCHICALLY below it. All files in UNIX are related to one another. The file system in UNIX is a collection of all these related files (ordinary, directory and device files) ORGANIZED in a hierarchical manner.

Correct option is (a) True

To explain I WOULD say: All physical DEVICES such as PRINTERS, hard disk are treated as files by the UNIX SYSTEM. Even the kernel, shell and main MEMORY is treated as a file by UNIX operating system.

Correct choice is (a) True

For explanation: Device FILES are nothing but special files which does not CONTAIN a stream of CHARACTERS but some attributes related to the devices which govern the operation of a device. The kernel READS this FILE for the attributes to perform operations on any device.

Correct option is (b) a directory containing details of the files and SUBDIRECTORIES it CONTAINS

For explanation I would say: A directory file contains no data but some details of the subdirectories and files that it contains. Directory files contain an ENTRY for every file and SUBDIRECTORY in it and each entry has some necessary INFORMATION regarding files and subdirectories.

Correct option is (c) filename and inode number

Explanation: EVERY ENTRY of the directory file CONTAINS INFORMATION about files and SUBDIRECTORIES and each entry has two components:

->Filename

->A unique identification number (called inode number).

The correct option is (a) ordinary file

For explanation I WOULD say: The most common file TYPE is an ordinary file or a regular file. It CONTAINS data as a stream of characters. Ordinary files are ALSO of two TYPES, text file and binary file.

Right ANSWER is (d) 3

Easy explanation: Files are DIVIDED into THREE major categories i.e. ordinary file, directory file and device file. The CHARACTERISTICS of these three categories of files differ from each other and each category has a predefined USE.

Correct choice is (a) True

The EXPLANATION: We can define a file as a stream of characters or a container for storing information. While WORKING in a UNIX environment, we came across three categories of files which are classified as- ORDINARY file, directory file and DEVICE file.