Lab 11
(Chapter 11)
Learning Objectives
- To learn how hard and soft
links are created and used
- To learn what impact do
creation of hard and soft links have on the file system structure
- To learn about the
relationship between links and file access permissions
- To learn about the contents
of hard and soft links
Lab Work
In this lab, you will learn how to
create hard and soft links in UNIX. For this purpose, you will use the file
system structure created in Lab 7 and smallFile that you created in Lab 9. We
are reproducing both here for your reference.
$ more smallFile
John Doe ECE
3.54 doe@jd.home.org 111.222.3333
James
Davis ECE 3.71 davis@jd.work.org 111.222.1111
Al Davis
CS 2.63 davis@a.lakers.org 111.222.2222
Ahmad Rashid
MBA 3.74 ahmad@mba.org 111.222.4444
Sam
Chu ECE 3.68 chu@sam.ab.com 111.222.5555
Arun Roy
SS 3.06 roy@ss.arts.edu 111.222.8888
Rick Marsh
CS 2.34 marsh@a.b.org 111.222.6666
James
Adam CS 2.77 jadam@a.b.org 111.222.7777
Art Pohm ECE
4.00 pohm@ap.a.org 111.222.9999
John Clark ECE
2.68 clark@xyz.ab.com 111.111.5555
Nabeel
Ali EE 3.56 ali@ee.eng.edu 111.111.8888
Tom Nelson ECE
3.81 nelson@tn.abc.org 111.111.6666
Pat King
SS 2.77 king@pk.xyz.org 111.111.7777
Jake Zulu
CS 3.00 zulu@jz.sa.org 111.111.9999
John Lee
EE 2.64 jlee@j.lee.com 111.111.2222
Sunil Raj ECE
3.36 raj@sr.cs.edu 111.111.3333
Charles Right EECS
3.31 right@cr.abc.edu 111.111.4444
Diane Rover ECE
3.87 rover@dr.xyz.edu 111.111.5555
Aziz Inan EECS
3.75 ainan@ai.abc.edu 111.111.1111
Lu John
CS 3.06 lu.john@xyz.org 111.333.1111
Lee Chow
EE 3.74 chow@lc.www.ord 111.333.2222
Adam
Giles SS 2.54 giles@cric.org 111.333.3333
Andy John EECS
3.98 john@aj.ece.edu 111.333.4444
$
- Log on to your UNIX system
- Remove
everything that you created under the temp directory in the above structure.
Show the session that you used for this purpose.
- Create
three directories under the temp directory: d1, d2, and d3. Make a copy of
smallFile in d1. Display long listing of smallFile and identify inode number,
access permissions, hard link count, and file size. Show your session.
- Change
directory to the d2 directory under the temp directory. Create a hard link to
smallFile in d1. Name the link file newFile.hard. Display long listing of
newFile.hard and compare its attributes with that of smallFile. How would you
confirm that smallFile and smallFile.hard are two names of the same file,
i.e., they are hard links to the same file? Show your session.
- Display
contents of smallFile by using the pathname for the hard link to the file,
smallFile.hard. You should be able to do this. Now, take away the read
permission for smallFile for yourself and try displaying the file again. What
happens? What do you conclude from the above exercise? Add the read permission
for yourself on the file and try redisplaying it. You should be able to do
this. Finally, make a backup copy of smallFile and delete smallFile. Now try
displaying its contents by using the pathname for smallFile.hard. What
happens? Does it make sense to you? Explain.
- Keep
~/temp/d2 as your current directory. Create a hard link to ~/temp/d2/smallFile.hard
and call it ~/temp/d1/smallFile. This means that you have undone the
rm ~/temp/d1/smallFile
command executed in 5 above and the hard link count for the file is back to 2.
Now create a soft link to ~/temp/d1/smallFile, called ~/temp/d2/smallFile.soft.
Display long listing of smallFile.soft and compare its attributes with that of
smallFile. How would you confirm that smallFile and smallFile.soft are two
different files? What do the sizes of the two files indicate? Show your
session.
- Display
contents of smallFile by using the pathname for the soft link to the file,
smallFile.hard. You should be able to do this. Now, take away the read
permission for smallFile for yourself and try displaying the file again. What
happens? What do you conclude from the above exercise? Add the read permission
for yourself on the file and try redisplaying it. You should be able to do
this. Finally, make a backup copy of smallFile and delete the original (i.e.,
smallFile). Now try displaying its contents by using the pathname for
smallFile.soft. What happens? Does it make sense to you? Explain.
- Log out.
