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File Processing Commands Worksheet – 15 Marks – Week 4
1. How do you know how many number ofusers currently logged into the system? (Not considering if any user is logged more than one time) (1)
A. who | uniq | sort | wc -l
B. who | cut -d' ' –f1 | uniq | wc -l
C. who | sort | uniq | wc -l
D. who | cut -d' ' –f1 | sort -u | wc -l
E. who | cut -d' ' –f1 | uniq -d | wc -l
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2. Create a file “employees.txt” using vi editor or pico.
(The file will have 6 fields, ID, Name, Designation, Dept, D.O.B, Salary separated by pipe)
Enter these lines in the file and save it.
2133|charles smith |Manager|sales|12/12/56| 90000
9576|Rob Thomson|director |production|03/12/50|130000
5778|David Blake |General Manager|marketing |04/19/43| 85000
2765|Rick Martin|director|personnel |05/11/47|120000
(Use cut command for the following questions A,B)
(in each one mark, ½ is for the command and ½ for the output)
A. Display the person's name, his designation and salary in the above file.
Show the command and output
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B: Display first 20 characters on each line in the above file.
Show the command and output
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3. How do you display the hour and minute from date command using cut utility (1)
Show the command and output
( ½ is for the command and ½ for the output)
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4. What is the difference between the following commands? (1)
$ who | grep 'mary'
and
$ who | grep '^mary'
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5. We know that all user information is stored in /etc/passwd where fields are delimited by a colon. Display only their userids using cut command. (userid is the first field in /etc/passwd file) Show only top 10 userids. (1)
Show the command and output
( ½ is for the command and ½ for the output)
Ans:
6. Create the following four files chapter1, chapter2, chapter3, chapter4 in your current directory and enter the following text:
Chapter1 :
This is the first line in this file
This chapter deals with the basic information of a UNIX system.
Chapter2 :
This is the first line in this file
This chapter deals with Unix System info and shell introduction.
Chapter3 :
This is the first line in this File System
This chapter deals with various Unix Systems.
Chapter4 :
This is the first line in this file
This chapter deals with kernel system.
The question is to search for a string "System" or "system" in the above files. Use wild cards in both pattern and file searching. (1)
Show the command and output
( ½ is for the command and ½ for the output)
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7. Show these commands and output:
A. Redirect man pages of ‘find’ command to a file called, find_manpages in /tmp directory.
B. Display lines not having the word “version” in the above file.(1)
(½ is for the command and ½ for the output)
Ans:
8. Which commandof the followingis correct ?(Some may work but does not make sense). (1)
a. cat file file > file3 | wc -l
b. cut -d ":" filename
c. ls -l | grep unix myfile
d. head filename | tail
e. find name "myfile.txt" -print
9. We know that ls -l command shows all the files in the current directory. How do you display only the directories, not files in the current directory. (You have to use ls command, but not find command) (1)
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10. How do you set only read permissions to user, group and others in octalmode for a file "myfile.txt" ? (1)
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11. You observed that some of your group members are fiddling with your file "myfile" and you wanted to remove the read permission to your group. How do you do? (1)
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12. Here isthe long listing of a file.
-rw-rw-rw- 2 Y435678 odms 22 Sep 02 12:03 myfile.txt
Is the above a file or a directory? To which group does it belong? (1)
Regular file, Y435678
file, Y435678
file, odms
directory, odms
directory, Y435678
Ans :
13. Here is another long listing of a file. (1)
-rw-r----- 1 Y435678 odms 20 Sep 02 17:03 file.txt.
What are the owner permissions?
read, execute
read, write
write, execute
all since s/he is the owner
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14. The file users_data has the following contents : (1)
Tom Smith 7.00 15 105.00
Rob Sheryl8.00 20 160.00
Ken Bradman 7.00 13 91.00
Peter Smith 6.00 15 90.00
Dennis Smith 8.00 13 104.00
Tom Dave 9.0012 108.00
How do you sort the above file and redirect the output to another file called sortedusers
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15. How do you list only duplicate lines in a file "myfile" (1)
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