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CUSTOMER_CODE SMUDE DIVISION_CODE SMUDE EVENT_CODE JAN2016 ASSESSMENT_CODE BC0056_JAN2016 QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 5311 QUESTION_TEXT Write a short Note on i. Devices ii. Links iii. HomeDirectory iv. The Current Directory v. Parent Directory SCHEME OF EVALUATION i.Devices: To provide applications with easy access to hardware devices. UNIX allows them to be used in much the same way as ordinary files. There are two types of devices in UNIX- block-oriented devices which transfer data in blocks and character – oriented devices that transfer data on a byte-by – byte basis. ii.Links: A link is a pointer to another file. There are two types of links – ahard link to a file is indistinguishable from the file itself. A soft link provides an indirect pointer or shortcut to a file. A soft link is implemented as a directory file entry containing a pathname. iii.The Home Directory: UNIX provides each user his own directory known as “home” directory. Within this, the users can store their own files, create subdirectories. This directory and its content is exclusive of the respective user. iv.The current directory: The current directory can be referred to by character (a full stop). This refers to your actual location in the file store hierarchy. When you log in, the current directory is set to your home directory. v.The Parent Directory: The parent directory is the directory immediately above the current directory. The parent directory can be referred to by the characters (two full stops). For example, to refer to the file test in the parent directory:../testRelative path names may also be constructed by progressively stepping back through parent directories using the construct. (2 marks each) QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 72491 QUESTION_TEXT Explain the following Directory and file handling commands in UNIX with their syntax. i. cp ii. mv iii. rm iv. cd v. cat SCHEME OF EVALUATION i. cp: cp is used to make copies of files or entire directories….. ii. mv: mv is used to rename files/directories and/or move them from one directory into another…… iii. rm: removes the specified files…………. iv. cd: changes your current working directory to path………….. v. cat: displays the contents of target-file(s) on the screen, one after the other……. Each 2 marks (syntax – 1, explanation -1) QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 72495 QUESTION_TEXT List and give the meaning of any 5 predefined special shell variables. Any 5 variable with meaning – each 2 marks SCHEME OF EVALUATION QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 72497 QUESTION_TEXT What are the layers of UNIX operating system? Explain. SCHEME OF EVALUATION The UNIX system is actually more than strictly an operating system. UNIX includes the traditional operating system components. In addition, a standard UNIX system includes a set of libraries and a set of applications. Sitting above the hardware are two components: the file system and process control. Next is the set of libraries. On top are the applications. The user has access to the libraries and to the applications. These two components are what many users think of as UNIX, because together they constitute the UNIX interface. The part of UNIX that manages the hardware and the executing processes is called the kernel. In managing all hardware devices, the UNIX system views each device as a file (called a device file). This allows the same simple method of reading and writing files to be used to access each hardware device. The file manages read and write access to user data and to devices, such as printers, attached to the system. It implements security controls to protect the safety and privacy of information. In executing processes, the UNIX system allocates resources (including use of the CPU) and mediates accesses to the hardware. (10 marks) QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 111205 QUESTION_TEXT In how many phases Fsck conducts a check? Briefly explain them. Phase 1 to 5 Explanation – Each 2 marks (10 marks) SCHEME OF EVALUATION QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID QUESTION_TEXT SCHEME OF EVALUATION 111214 Explain the mounting and un-mounting process in UNIX The mount Command (5 marks) The basic format of mount command: # mount device mountpoint Options: -a: Mount all the file systems listed in /etc/fstab. Except those marked as noauto keyword excluded by the -t flag, or those that are already mounted. -f: Forces the mount of an unclean file system (dangerous), or forces the revocation of write access when downgrading a file system’s mount status from read-write to read-only. -r: Mounts the file system read-only. -t fstype: Mounts the given file system as the given file system type -U: Update mounts options on the file system. -v: Be verbose. -w: Mounts the file system read-write. Unmount: Un-mounting File Systems (5 marks) Unmounting is achieved with the unmount command which requires either the file system name or the mount point as argument. umount /oracle umount /fdev/hda3 umount/dev/dsk/cOt3dOs5 Unmounting a file system is not possible if you have a file open in it. Further, just as you can’t remove a directory unless you are placed in a directory above it, you can’t unmount a file system unless you are placed above it. All forms take -f to force unmounting, and -v for verbosity. -a and -A are used to unmount all mounted file systems, -A, however, does not attempt to unmount the root tile system.