UNIX CLASS PPT CHAPTER 5

Directions: Read each of the following statements. If you think a statement is true, select True. If you think a statement is false, select False.1. The directory structure is arranged in levels and is known as a hierarchicalstructure.a. Trueb. False2. Your login name and your home directory name are usually the same.a. Trueb. False3. Every UNIX file structures has a root directory named / (slash).a. Trueb. False4. Files in your current directory are immediately accessible. Files on the otherdirectories must be identified by their pathnames.a. Trueb. False5. Absolute and relative pathnames are the same and indicate the same pathname.a. Trueb. False6. If you have just logged in, your home, current or working directories arethe same.a. Trueb. False7. In UNIX filenames XYZ and xyz are indicating the same filename.a. Trueb. False8. In UNIX filename extension is absolutely necessary.a. Trueb. False9. The pwd command prints your working directory on the printer.a. Trueb. False10. The cd command returns you to the root directory.a. Trueb. False11. The invisible files are the files that only the owner can see.a. Trueb. False12. You can use only one command option at a time on the command line.a. Trueb. False13. You can use the vi editor or the cat command to look at the content of a file.a. Trueb. False14. You can use the vi editor or the cat command to create a file.a. Trueb. False15. After the print command is issued, there is no way to cancel the print job.a. Trueb. False16. The rmdir command (with no options) can only remove empty directories.a. Trueb. False17. The / at the beginning of a pathname stands for the root directory.a. Trueb. False18. The name .HIDDEN is an example of a hidden file.a. Trueb. False19. Ý(dot) and .. (dot dot) represent the current and a level higher directoriesrespectively.a. Trueb. False20. To cancel a print job, you only have to turn the printer off.a. Trueb. FalseDirections:Match the following commands to the corresponding descriptions. Place the letter that indicates your answer on the line in front of each command.a. absolute pathname to the file called xyzb. changes the directory to the parent of the current directoryc. lists current directory files including the invisible filesd. sends xyz file to the line printere. deletes the directory called xyzf. displays the content of the file called xyzg. displays the current directory pathnameh. cancels the printing job on the lp1 printeri. confirms the deletion of the xyz file before deleting itj. lists the current directory in long formatk. lists files across the page separated by commasl. changes the current directory to the HOME directorym. removes all subdirectories and files under the current directoryn. shows name of the default printero. shows status of the printing requestsp. sends mail to the user mailbox after completion of the print requestq. prints on a specific (named) printer (Linux)r. displays usage message for the rm command (Linux)s. creates two levels of directories under the current directory(Linux)t. prints the specified title on the banner page (Linux)21. _____ lp xyz22. _____ cat xyz23. _____ rm -i xyz24. _____ /david/xyz25. _____ cancel lp126. _____ ls -l27. _____ cd ..28. _____ ls -a29. _____ rmdir xyz30. _____ pwd31. _____ lpstat -d32. _____ rm --help33. _____ lpr -p filename34. _____ rm -r *35. _____ lpstat36. _____ ls -m37. _____ cd38. _____ mkdir --parent xx/yy39. _____ lpr -T40. _____ lp -m filenameDirections: Select the letter that indicates the best answer for the question.41. The command to show your current directory pathname isa. pcdb. ls -ac. pwdd. lp pwde. ls pwd42. The command to create a directory called xyz isa. mkdir xyzb. mk xyz dirc. md xyzd. dir xyze. MKDIR xyz43. The command to delete a file called xyz with confirmation option isa. del xyzb. rm xyzc. rm -c xyzd. rm -i xyze. rm xyz -i44. If your current directory pathname is /usr/david, the command ls ..a. displays the current directoryb. lists files in the working directoryc. lists files in david directoryd. lists files in the usr directorye. displays invalid command message45. Which of the following commands is not a correct use of the options?a. ls -amFb. ls -a -Cc. lp -tHELLO xyzd. ls ae. all of the above46. Which of the following filenames is not a correct filename?a. XYZ.xyzb. XYZ>> xyzc. Xyzd. X.Y.Ze. all of the above47. If your current directory is /usr/david, the command cd /changes your currentdirectory toa. rootb. usrc. davidd. /usre. none of the above48. The command to print the files XYZ and xyz isa. lp XYZ, xyzb. print XYZ and xyzc. P xyz, XYZd. lp XYZ xyze. lp -2 XYZ49. The command to check the status of your print job isa. lpstat printersb. lpstat jobsc. lpstatd. lp statuse. status printers50. Which one of the following pathnames is considered an absolute pathname?a. absolute/xyzb. /bin/usr/u/se-binc. david/memo/cd. Ý/../xyze. ÝÝ/xyz/xxx/memo51. The command to print a file on a specific printer isa. lp -d filenameb. lp filename printer-namec. lp -d printer-name filenamed. print filename ptr1e. p -d printer-name filename52. The command to obtain the name of the default printer isa. lpstat -db. lpstat printer-namec. lp -dd. print default ptre. printer53. The Linux command to print on a specific (named) printer isa. lpr -d filenameb. lpr filename printer-namec. lpr -p printer-name filenamed. print filename ptr1e. pr -d printer-name filename54. The command to delete a directory and all the subdirectories and files init isa. rm -r directory-nameb. rm directory-namec. rm -all directory-named. rm -sub directory-namee. rm all55. The Linux command to delete a directory and all the subdirectories and filesin it isa. rm --recursive directory-nameb. rm --r directory-namec. rm --all directory-named. rm --sub directory-namee. rm --all56. The Linux command to obtain help screen for the rm command isa. rm --hb. rm --helpc. help rmd. help --rme. rm help57. The command to list a hierarchy of directories isa. ls -R directory -nameb. ls -a directory -namec. ls -all directory -named. ls -hierarchy 3directory -namee. ls directoryÄname all58. The Linux command to list a hierarchy of directories isa. ls --R directory -nameb. ls --a directory -namec. ls --all directory -named. ls --hierarchy directory -namee. ls --recursive directoryÄname59. The command to create 2 levels of directories isa. mkdir -p level-1/level-2b. mkdir -l level-1/level-2c. mkdir -2 level-1/level-2d. mkdir -h level-1/level-2e. mkdir -p level-1 level-260. The Linux command to create 2 levels of directories isa. mkdir --parent level-1/level-2b. mkdir --l level-1/level-2c. mkdir -l level-1/level-2d. mkdir -hierarchy level-1/level-2e. mkdir -p level-1 level-21. True2. True3. True4. True5. False6. True7. False8. False9. False10. False11. False12. False13. True14. True15. False16. True17. True18. True19. True20. False21. d22. f23. i24. a25. h26. j27. b28. c29. e30. g31. n32. r33. q34. m35. o36. k37. l38. s39. t40. p41. c42. a43. d44. d45. d46. b47. a48. d49. c50. b51. c52. a53. c54. a55. a56. b57. a58. e59. a60. a。

drwxr-xr-x 2 root other 512 Oct 20 20:00 temp -rw-r--r-- 1 root other 23 Dec 20 16:06 abc.txt
文件 类型 文件
权限
属主 组
链接 数
文件 大小
文件 创建 日期 时间
文件 名
-
P13
UNIX文件信息
文件类型：－
1983年，贝尔实验室发布第一个商业版本的UNIX，系统V的版本1, 即SVR1。
-
P44
UNIX标准版本
传统的UNIX标准版本主要如下两个： UNIX System V 原是AT&T公司制定的标准版本，后来成为工业
标准。目前流行版本是SVR 3.2、SVR 4.0、SVR 4.2 (SVR的全称 是System V Release) 。SCO UNIX就是采用的就是UNIX System V。
UNIX操作系统提示符一般为”#”。
进程(Process) 正在执行的程序。UNIX允许多个进程同时存在，每个进程
都有唯一代号称为进程标识符(pid --- process id)。
-
P28
几个基本概念
前台进程(Foreground process) 可以和用户直接进行人机交互的进程。前台进程程序可以接
3 设备文件 代表某种设备，一般放在/dev目录下，如 /dev/cd0表示光驱。设备文件可分为块设备文件和字符设备 文件，块设备文件以区块为输入输出单元，如磁盘；字符设 备文件是以字符作为输入输出单元，如串口。
4 符号链接文件包含一指针，指向文件的位置。
-
P12
UNIX文件信息
UNIX文件信息包括文件的类型、名字、大小、最近修改日期、操 作权限等等。如：

9
9
File Permissions
• There are 3 different categories of users for which different permissions can be set:
- User: The user who owns the file
- Group: The group thae Permissions
• A file’s permissions describe which users are allowed to manipulate it
• There are 3 types of permissible acts relating to files
- Read: access the contents of a file; list the files in a directory - Write: modify the contents of a file;
Remove Set
Symbol r w x
Meaning read write
execute
• chmod uses the above set of symbols in various combinations to set permissions - chmod ugo=rwx somefile will set read, write, and execute permissions for user, group, and other - chmod go-rwx somefile will remove read, write, and execure permissions for group and other

（2）存储器管理 OS按照一定的策略为用户作业分配存 储空间，记录主存储器的使用情况，并对主存储器中的 信息提供保护，在该作业执行结束后收回它所占用的内 存单元以便其他程序使用。
5 2020/4/22
（3）输入输出设备管理 OS记录系统中各个输入输出设 备的状态，按照各个设备的不同特点采取不同的策略分 配和回收外部设备,以及控制外部设备的操作。
（4）文件管理 OS对存放在计算机中的信息进行逻辑组 织和物理组织、维护文件目录的结构以及实现对文件的 各种操作。例如，可向用户提供创建文件、撤销文件、 读写文件、打开和关闭文件等功能。有了文件管理，用 户可以按文件名存取数据而不必了解这些数据的确切物 理位置。文件管理还可以允许用户在创建文件时规定文 件的使用权限，这样数据的安全性也可得到保证。
15 2020/4/22
3.1 基本命令格式
在Shell提示符下，就可以输入UNIX命令。UNIX命令的基本格式如下：
command 参数1 参数2 ... 参数n
UNIX命令由一个命令（command）和零到多个参数构成，命令和参数之间，以及参数 与参数之间用空格隔开。UNIX的命令格式和DOS的命令格式相似，但UNIX的命令 区分大小写，且命令和参数之间必须隔开。如：对DOS来说是以下四条命令是相同 的：
①内核。内核是UNIX操作系统的核心，它 的作用是调度和管理计算机系统的各种资源。 它划分为44个源代码文件、233个模块，其 功能分别是进程通信、系统调用、输入输出 管理以及文件管理。
9 2020/4/22
UNIX的组成
②文件系统。文件系统在UNIX操作系统中主要用 来组织并管理数据资源。UNIX的文件系统采用树 状的层次结构，它的第一层是树的根/，第二层通 常包括etc目录（重要的系统配置文件）、bin目录 （其中有UNIX的常用命令）。usr目录（系统资 源文件）及lib目录（函数库目录）等。目前UNIX 文件系统能支持虚拟文件系统、网络文件系统、远 程文件系统、安全性文件系统及光盘文件系统等不 同类型的文件系统。