Transcript CS311 Introduction to Operating Systems I - Summer 2009

CS311 – Lecture 18 Outline
• Midterm 2 Review
Note: These lecture notes are not intended replace your notes. This is
what I expect your notes to already look like, but with more explanation as
needed.
Lecture 18
CS311 – Operating Systems 1
1
Midterm 2 study guide
• You will be reading / writing code with any of the
following system calls (review fileIO.c on the
Schedule page or your Project 3 code):
– open: know when to use or not use O_CREAT,
O_CREAT|O_EXCL; know that you HAVE to use exactly one
of O_RDWR, O_RDONLY, O_WRONLY
– close
– lseek
– read (you could be asked to deal with structs, ints, chars,
strings, ...)
– write (you could be asked to deal with structs, ints, chars,
strings, ...)
Lecture 18
CS311 – Operating Systems 1
2
Midterm 2 study guide
• Be able to use the open system call to create a
lockfile to keep other processes out of a critical
section.
• Be able to write code that calls perror if any of the
above calls fails.
Lecture 18
CS311 – Operating Systems 1
3
Midterm 2 study guide
• What information is contained in an i-node? What
information is NOT contained in an i-node?
– What do the r, w, x permissions let you do to a regular file?
– What do the r, w, x permissions let you do to a directory file?
• Given block size and inode structure, what is the size
of the largest file that can be stored in this File
System?
Lecture 18
CS311 – Operating Systems 1
4
Midterm 2 study guide
• What is the detailed explanation of how a file system
finds the file readMe.txt from the following absolute
path? /nfs/dirA/readMe.txt
• If I give you a sequence of commands (cp, mv, ln, ln
with -s option, rm, echo "hi" > aFile, ...)
– Can you draw what the directory's data block looks like?
What the inodes look like? What the other file's data
blocks look like?
Lecture 18
CS311 – Operating Systems 1
5
Midterm 2 study guide
• Given a makefile, you should be able to write
what appears on the screen after commands
such as:
make abc
make
touch something.c
make
Lecture 18
CS311 – Operating Systems 1
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Midterm 2 study guide
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Organization of Unix
Process state diagram
Process image in virtual memory diagram
Unix / Linux filesystem security via what 2
mechanisms?
• multprogramming and timesharing
If we didn't have a multiprogramming OS what would
be missing?
– 1) Only one user at a time
– 2) That one user could run only one process (application)
at a time
Lecture 18
CS311 – Operating Systems 1
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