Linux筆試題（英文版）

1. Q. How do you list files in a directory?
A: ls
ls
文法：ls   [選項] 路徑名稱
    -a 顯示所有檔案及目錄 (ls內定將檔案名或目錄名稱開頭為"."的視為隱藏檔,不會列出)
　　-l 除設定檔名稱外,亦將檔案型態,許可權,擁有者,檔案大小等資訊詳細列出
　　-r 將檔案以相反次序顯示(原定依英文字母次序)
　　-t 將檔案依建立時間之先後次序列出
　　-A 同 -a ,但不列出 "." (目前目錄) 及 ".." (父目錄)
　　-F 在列出的設定檔名稱後加一符號；例如可執行檔則加 "*", 目錄則加 "/"

　　-R 若目錄下有檔案,則以下之檔案亦皆依序列出

2. Q. How do you list all files in a directory, including the hidden files?

A: ls-a

3. Q. How do you find out all processes that are currently running?

A: ps -f

4. Q. How do you find out the processes that are currently running or a particular user?

A: ps -au username

-A 列出所有的行程
-w 顯示加寬可以顯示較多的資訊
-au 顯示較詳細的資訊
-aux 顯示所有包含其他使用者的行程
-U<使用者識別碼> 　列出屬於該使用者的進程的狀況，也可使用使用者名稱稱來指定。
U<使用者名稱稱> 　列出屬於該使用者的進程的狀況。

5. Q. How do you kill a process?

A: kill pid

6. Q. What would you use to view contents of the file?

A: less filename
cat filename
pg filename
pr filename
more filename
most useful is command: tail file_name - you can see the end of the log file

7. Q. What would you use to edit contents of the file?

A: vi file

8. Q. What would you use to view contents of a large error log file?

A: tail  -10 file_name   ( last 10 rows)

9. Q. How do you log in to a remote Unix box?

A: Using telnet server_name or ssh -l ( ssh - OpenSSH SSH client (remote login program))

10.Q. How do you get help on a UNIX terminal?

A: man command_name
info command_name (more information)

11.Q. How do you list contents of a directory including all of its subdirectories, providing full details and sorted by modification time?

A: ls -lac
-a all entries
-c by time

12.Q. How do you create a symbolic link to a file (give some reasons of doing so)?

A:  ln /../file1 Link_name
Links create pointers to the actual files, without duplicating the contents of the files. That is, a link is a way of providing another name to the same file. There are two types of links to a file:Hard link, Symbolic (or soft) link;

13.Q. What is a filesystem?

A: Sum of all directories called file system. A file system is the primary means of file storage in UNIX. File systems are made of inodes and superblocks.

14.Q. How do you get its usage (a filesystem)?

A:By storing and manipulate files.

15.Q. How do you check the sizes of all users? home directories (one command)?

A: du -s

df

16.Q. How do you check for processes started by user 'pat'?
A: ps -fu pat   (-f -full_format u -user_name )

17.Q. How do you start a job on background?

A: bg %4

18 Q. What utility would you use to replace a string '2001' for '2002' in a text file?

A: grep kde

19. Q. What utility would you use to cut off the first column in a text file? 

A: awk kde

20. Q. How to copy file into directory?

A: cp dir

21. Q. How to remove directory with files?
A: rm -rf directory_name

22. Q. What is the difference between internal and external commands?
A: Internal commands are stored in the same level as the operating system while external commands are stored on the hard disk among the other utility programs.

23. Q. List the three main parts of an operating system command:

A: The three main parts are the command, options and arguments.

24  Q. What is the difference between an argument and an option (or switch)?
A: An argument is what the command should act on: it could be a filename, directory or name. An option is specified when you want to request additional information over and above the basic information each command supplies.

25. Q. What is the purpose of online help?
A: Online help provides information on each operating system command, the syntax, the options, the arguments with descriptive information.

26.  Q. Name two forms of security.
    A.  Two forms of security are Passwords and File Security with permissions specified.

27. Q. What command do you type to find help about the command who?
    A. $ man who

28. Q. What is the difference between home directory and working directory?
    A. Home directory is the directory you begin at when you log into the system. Working directory can be anywhere on the system and it is where you are currently working.

29. Q. Which directory is closer to the top of the file system tree, parent directory or current directory?
    A. The parent directory is above the current directory, so it is closer to the root or top of the file system.

30. Q. Given the following pathname:
$ /business/acctg/payable/supplier/april
a) If you were in the directory called acctg, what would be the relative pathname name for the file called april?
b) What would be the absolute pathname for april?
A:
a) $ payable/supplier/april
b) $ /business/acctg/payable/supplier/april

31. Q. Suppose your directory had the following files:
help.1 help.2 help.3 help.4 help.O1 help.O2
aid.O1 aid.O2 aid.O3 back. 1 back.2 back.3
a) What is the command to list all files ending in 2?
b) What is the command to list all files starting in aid?
c) What is the command to list all "help" files with one character extension?
A:
a) ls *2
b) ls aid.*
c) ls help.?

32. Q. What are two subtle differences in using the more and the pg commands?
    A.  With the more command you display another screenful by pressing the spacebar, with pg you press the return key.
      The more command returns you automatically to the UNIX shell when completed, while pg waits until you press return.

33. Q. When is it better to use the more command rather than cat command?
    A. It is sometimes better to use the more command when you are viewing a file that will display over one screen.

34. Q. What are two functions the move mv command can carry out?
    A. The mv command moves files and can also be used to rename a file or directory.

35. Q. Name two methods you could use to rename a file.
A: Two methods that could be used:
a. use the mv command
b. copy the file and give it a new name and then remove the original file if no longer needed.

36. The soccer league consists of boy and girl teams. The boy file names begin
with B, the girl teams begin with G. All of these files are in one directory
called "soccer", which is your current directory:
Bteam.abc Bteam.OOl Bteam.OO2 Bteam.OO4
Gteam.win Gteam.OOl Gteam.OO2 Gteam.OO3
Write the commands to do the following:
a) rename the file Bteam.abc to Bteam.OO3.
b) erase the file Gteam. win after you have viewed the contents of the file
c) make a directory for the boy team files called "boys", and one for the girl team files
called" girls"
d) move all the boy teams into the "boys" directory
e) move all the girl teams into the "girls" directory
f) make a new file called Gteam.OO4 that is identical to Gteam.OOl
g) make a new file called Gteam.OO5 that is identical to Bteam.OO2
  A.
a) mv Bteam.abc Bteam.OO3.
b) cat Gteam.win -or- more Gteam.win
rm Gteam. win
c) mkdir boys
mkdir girls
d) mv Bteam* boys
e) mv Gteam* girls
f) cd girls
cp Gteam.OO1 Gteam.OO4
g) There are several ways to do this. Remember that we are currently in the directory
/soccer/girls.
cp ../boys/Bteam.OO2 Gteam.OO5
or
cd ../boys
cp Bteam.OO2 ../girls/Gteam.OO5

37. Q. What metacharacter is used to do the following:
1.1 Move up one level higher in the directory tree structure
1.2 Specify all the files ending in .txt
1.3 Specify one character
1.4 Redirect input from a file
1.5 Redirect the output and append it to a file
    A.
1. 1.1 double-dot or ..
1.2 asterisk or *
1.3 question or ?
1.4 double greater than sign: >>
1.5 the less than sign or < 

38. Q. Which of the quoting or escape characters allows the dollar sign ($) to retain its special meaning?
    A. The double quote (") allows the dollar sign ($) to retain its special meaning.
Both the backslash (\) and single quote (') would remove the special meaning of the dollar sign. 

39. Q. What is a faster way to do the same command?
mv fileO.txt newdir
mv filel.txt newdir
mv file2.txt newdir
mv file3.txt newdir
    A. A shortcut method would be:   mv file?.txt newdir 

40. Q. List two ways to create a new file:
    A.
a. Copy a file to make a new file.
b. Use the output operator e.g. ls -l > newfile.txt 

41. Q. What is the difference between > and >> operators?
    A. The operator > either overwrites the existing file (WITHOUT WARNING) or creates a new file.
The operator >> either adds the new contents to the end of an existing file or creates a new file.

44. Write the command to do the following:
44.1 Redirect the output from the directory listing to a printer.
44.2 Add the file efg.txt to the end of the file abc.txt.
44.3 The file testdata feeds information into the file called program
44.4 Observe the contents of the file called xyz.txt using MORE.
44.5 Observe a directory listing that is four screens long.
     A.
44.1 ls > lpr
44.2 cat efg.txt >> abc.txt
44.3 program < testdata
44.4 more < xyz.txt
44.5 ls > dirsave | more
46. Q. How can you see all mounted drives?
    A. mount -l

47. Q. How can you find a path to the file in the system?
    A. locate file_name (locate - list files in databases that match a pattern)

48. Q. What Linux  HotKeys do you know?
    A. Ctrl-Alt-F1    Exit to command prompt
       Ctrl-Alt-F7 or F8    Takes you back to KDE desktop from command prompt
       Crtl-Alt-Backspace    Restart XWindows
       Ctrl-Alt-D    Show desktop

49. Q. What can you tell about the tar Command?
    A. The tar program is an immensely useful archiving utility. It can combine an entire directory tree into one large file suitable for transferring or compression.

50.  Q. What types of files you know?
     A. Files come in eight flavors:
Normal files
Directories
Hard links
Symbolic links
Sockets
Named pipes
Character devices
Block devices

51.  Q. How to copy files from on PC to another on the same network
     A. Use the following command:scp yur_file you_login@your_IP
example: copy .conf file from your PC  to alex computer-
 scp /etc/X11/xorg.conf alex@10.0.10.169:

53. Q. If you would like to run two commands in sequence what operators you can use?
     A. ; or && the difference is:
if you separate commands with ; second command will be run automatically.
if you separate commands with && second command will be run only in the case the first was run successfully.

54.  Q. How you will uncompress the file?
      A. Use tar command (The GNU version of the tar archiving utility):
tar -zxvf file_name.tar.gz

55. Q.How do you execute a program or script, my_script in your current directoty?
    A. ./my_script

56. Q.How to find current time configuration in the file my_new.cfg
    A. grep time my_new.cfg

Grep searches the named input files (or standard input if no files are named, or the file name - is given) for lines containing a match to the given pattern.

59.  Q. How to find difference in two configuration files on the same server?
     A. Use diff command that is compare files line by line
diff -u /usr/home/my_project1/etc/ABC.conf /usr/home/my_project2/etc/ABC.conf

61.  Q. Please write a loop for removing all files in the current directory that contains a word 'log'
     A. for i in *log*; do rm $i; done

62.  Question: How to switch to a previously used directory?
     Answer:   cd -