Operating System Concepts
Chapter 11 { File-System Interface
Based on the 9th Edition of:
Abraham Silberschatz, Peter B. Galvin and Jreg Gagne:. Operating System
Concepts
Department of Information Technology, College of Business, Law & Governance
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Learning Objectives
To explain the function of file systems
To describe the interfaces to file systems
To discuss file-system design trade-offs, including access
methods, file sharing, file locking, and directory structures
To explore file-system protection
Chapter 11 { File-System Interface Operating System Concepts 2
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Outline
1 File Concept
2 Access Methods
3 Directory and Disk Structure
4 File-System Mounting
5 File Sharing
6 Protection
Chapter 11 { File-System Interface Operating System Concepts 3
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
File Concept
Contiguous logical address space
Types:
Data ) numeric; character; binary
Program
Contents defined by file’s creator
Many types |Consider text file, source file, executable file
Chapter 11 { File-System Interface Operating System Concepts 4
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
File Concept
File Types,
Name and
Extension
le type usual extension function
ready-to-run machinelanguage program
executable exe, com, bin
or none
compiled, machine
language, not linked
object obj, o
binary le containing
audio or A/V information
multimedia mpeg, mov, mp3,
mp4, avi
related les grouped into
one le, sometimes compressed, for archiving
or storage
archive rar, zip, tar
ASCII or binary le in a
format for printing or
viewing
print or view gif, pdf, jpg
libraries of routines for
programmers
library lib, a, so, dll
various word-processor
formats
word processor
docx
commands to the command
interpreter
batch bat, sh
markup xml, html, tex textual data, documents
source code in various
languages
source code c, cc, java, perl,
asm
xml, rtf,
Chapter 11 { File-System Interface Operating System Concepts 5
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
File Concept | File Attributes
Name { only information kept in human-readable form
Identifier { unique tag (number) identifies file within file
system
Type { needed for systems that support different types
Location { pointer to file location on device
Size { current file size
Protection { controls who can do reading, writing, executing
Time, date, and user identification { data for protection,
security, and usage monitoring
Information about files are kept in the directory structure, which is
maintained on the disk
Chapter 11 { File-System Interface Operating System Concepts 6
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
File Concept | File Operations
File is an abstract data type that takes following operations
Create
Write { at write pointer location
Read { at read pointer location
Reposition within file { seek
Delete
Truncate
Open(Fi) { search the directory structure on disk for entry Fi,
and move the content of entry to memory
Close (Fi) { move the content of entry Fi in memory to
directory structure on disk
Chapter 11 { File-System Interface Operating System Concepts 7
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
File Concept | File Operations
Open Files
Several pieces of data are needed to manage open files:
Open-file table: tracks open files
File pointer: pointer to last read/write location, per process
that has the file open
File-open count: counter of number of times a file is open |to
allow removal of data from open-file table when last processes
closes it
Disk location of the file: cache of data access information
Access rights: per-process access mode information
Chapter 11 { File-System Interface Operating System Concepts 8
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
File Concept | File Operations
Open File Locking
Provided by some operating systems and file systems
|Similar to reader-writer locks
Shared lock similar to reader lock { several processes can
acquire concurrently
Exclusive lock similar to writer lock
Mediates access to a file and could be Mandatory or Advisory:
Mandatory { access is denied depending on locks held and
requested (used in Windows)
Advisory { processes can find status of locks and decide what
to do (Used in UNIX)
Chapter 11 { File-System Interface Operating System Concepts 9
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
File Concept | File Structure
None { sequence of words, bytes
Simple record structure { Lines; Fixed length; Variable length
Complex Structures { Formatted document; Relocatable load
file
Who decides:
Operating system
Program
Chapter 11 { File-System Interface Operating System Concepts 10
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 A(n) file is a sequence of functions.
A. text
B. source
C. object
D. executable
Answer:
Chapter 11 { File-System Interface Operating System Concepts 11
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 A(n) file is a sequence of functions.
A. text
B. source
C. object
D. executable
Answer: B
Chapter 11 { File-System Interface Operating System Concepts 11
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 A(n) file is a sequence of functions.
A. text
B. source
C. object
D. executable
Answer: B
2 True or False { Windows systems employ mandatory
locking.
Answer:
Chapter 11 { File-System Interface Operating System Concepts 11
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 A(n) file is a sequence of functions.
A. text
B. source
C. object
D. executable
Answer: B
2 True or False { Windows systems employ mandatory
locking.
Answer: True
Chapter 11 { File-System Interface Operating System Concepts 11
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 A(n) file is a sequence of functions.
A. text
B. source
C. object
D. executable
Answer: B
2 True or False { Windows systems employ mandatory
locking.
Answer: True
3 True or False { As a general rule, UNIX systems employ
mandatory locks.
Answer:
Chapter 11 { File-System Interface Operating System Concepts 11
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 A(n) file is a sequence of functions.
A. text
B. source
C. object
D. executable
Answer: B
2 True or False { Windows systems employ mandatory
locking.
Answer: True
3 True or False { As a general rule, UNIX systems employ
mandatory locks.
Answer: False
Chapter 11 { File-System Interface Operating System Concepts 11
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 A(n) file is a sequence of bytes organized into blocks
understandable by the system’s linker.
A. text
B. source
C. object
D. executable
Answer:
Chapter 11 { File-System Interface Operating System Concepts 12
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 A(n) file is a sequence of bytes organized into blocks
understandable by the system’s linker.
A. text
B. source
C. object
D. executable
Answer: C
Chapter 11 { File-System Interface Operating System Concepts 12
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 A(n) file is a sequence of bytes organized into blocks
understandable by the system’s linker.
A. text
B. source
C. object
D. executable
Answer: C
2 A(n) file is a series of code sections that the loader can
bring into memory and execute.
A. text
B. source
C. object
D. executable
Answer:
Chapter 11 { File-System Interface Operating System Concepts 12
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 A(n) file is a sequence of bytes organized into blocks
understandable by the system’s linker.
A. text
B. source
C. object
D. executable
Answer: C
2 A(n) file is a series of code sections that the loader can
bring into memory and execute.
A. text
B. source
C. object
D. executable
Answer: D
Chapter 11 { File-System Interface Operating System Concepts 12
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Access Methods
Sequential Access
read next
write next
reset
no read after last write (rewrite)
Direct Access |file is fixed length logical records
read n
write n
position to n
read next
write next
rewrite n
n = relative block number
Relative block numbers allow OS to decide where file should
be placed |See allocation problem in Chapter 12
Chapter 11 { File-System Interface Operating System Concepts 13
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Access Methods
Sequential-Access File
beginning end current position
rewind
read or write
Chapter 11 { File-System Interface Operating System Concepts 14
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Access Methods
Simulation of Sequential-Access on Direct-Access File
sequential access
reset
read_next
write_next
cp 0;
read cp ;
cp cp 1;
write cp;
cp cp 1;
implementation for direct access
Chapter 11 { File-System Interface Operating System Concepts 15
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Access Methods | Other Access Methods
Can be built on top of base methods
General involve creation of an index for the file
Keep index in memory for fast determination of location of
data to be operated on
If too large, index (in memory) of the index (on disk)
IBM indexed sequential-access method (ISAM)
Small master index, points to disk blocks of secondary index
File kept sorted on a defined key
All done by the OS
VMS operating system provides index and relative files as
another example (see next slide)
Chapter 11 { File-System Interface Operating System Concepts 16
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Access Methods
Example of Index and Relative Files
index file relative file
Smith
last name
smith, john social-security age
logical record
number
Adams
Arthur
Asher
•••
Chapter 11 { File-System Interface Operating System Concepts 17
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 The simplest file access method is .
A. sequential access
B. logical access
C. relative access
D. direct access
Answer:
Chapter 11 { File-System Interface Operating System Concepts 18
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 The simplest file access method is .
A. sequential access
B. logical access
C. relative access
D. direct access
Answer: A
Chapter 11 { File-System Interface Operating System Concepts 18
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 The simplest file access method is .
A. sequential access
B. logical access
C. relative access
D. direct access
Answer: A
2 Which of the following is true of the direct-access method?
A. It is the most common mode of access.
B. It allows programs to read and write records in no particular
order.
C. Files are made up of variable-length records.
D. It is not a good method for accessing large amounts of data
quickly.
Answer:
Chapter 11 { File-System Interface Operating System Concepts 18
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 The simplest file access method is .
A. sequential access
B. logical access
C. relative access
D. direct access
Answer: A
2 Which of the following is true of the direct-access method?
A. It is the most common mode of access.
B. It allows programs to read and write records in no particular
order.
C. Files are made up of variable-length records.
D. It is not a good method for accessing large amounts of data
quickly.
Answer: B
Chapter 11 { File-System Interface Operating System Concepts 18
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Directory and Disk Structure
A collection of nodes containing information about all files
F 1 F 2
F 3
F 4
F n
Directory
Files
Both the directory structure and the files reside on disk
Chapter 11 { File-System Interface Operating System Concepts 19
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Directory and Disk Structure
Disk can be subdivided into partitions
Disks or partitions can be RAID protected against failure
Partitions also known as minidisks, slices
Entity containing file system known as a volume
Each volume containing file system also tracks that file
system’s info in device directory or volume table of contents
As well as general-purpose file systems there are many
special-purpose file systems, frequently all within the same
operating system or computer
Chapter 11 { File-System Interface Operating System Concepts 20
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Directory and Disk Structure
A Typical File-System Organization
directory directory
directory
files
partition A
partition B
partition C
files
disk 1
disk 2
disk 3
files
Chapter 11 { File-System Interface Operating System Concepts 21
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Directory and Disk Structure
Types of File Systems
We mostly talk of general-purpose file systems; But systems
frequently have many file systems, some general and some
special-purpose
Consider Solaris has
tmpfs { memory-based volatile FS for fast, temporary I/O
objfs { interface into kernel memory to get kernel symbols for
debugging
ctfs { contract file system for managing daemons
lofs { loopback file system allows one FS to be accessed in
place of another
procfs { kernel interface to process structures
ufs, zfs { general purpose file systems
Chapter 11 { File-System Interface Operating System Concepts 22
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Directory and Disk Structure
Operations Performed on Directory
Search for a file
Create a file
Delete a file
List a directory
Rename a file
Traverse the file system
Chapter 11 { File-System Interface Operating System Concepts 23
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Directory and Disk Structure
Directory Organization
The directory is organized logically to obtain
Efficiency { locating a file quickly
Naming { convenient to users
Two users can have same name for different files
The same file can have several different names
Grouping { logical grouping of files by properties, (e.g., all
Java programs, all games, . . . )
Chapter 11 { File-System Interface Operating System Concepts 24
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Directory and Disk Structure
Single-Level Directory |A single directory for all users
cat
files
directory bo a test data mail cont hex records
Naming problem
Grouping problem
Chapter 11 { File-System Interface Operating System Concepts 25
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Directory and Disk Structure
Two-Level Directory |Separate directory for each user
cat bo a test a x data a
user 1 user 2 user 3 user 4
user file data a test
directory
master file
directory
Path name |Can have the same file name for different user
Efficient searching
No grouping capability
Chapter 11 { File-System Interface Operating System Concepts 26
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Directory and Disk Structure

list obj spell
stat mail dist find count hex reorder
root spell bin programs
p e mail
prog copy prt exp reorder list find
last first
hex count
all
Chapter 11 { File-System Interface Operating System Concepts 27
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Directory and Disk Structure
Tree-Structured Directories (Cont.)
Efficient searching
Grouping Capability
Current directory (also known as working directory)
cd /spell/mail/prog
type list
Chapter 11 { File-System Interface Operating System Concepts 28
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Directory and Disk Structure
Tree-Structured Directories (Cont.)
Absolute or relative path name
Creating a new file is done in current directory
Delete a file
rm <file-name>
Creating a new subdirectory is done in current directory
mkdir <dir-name>
Deleting ’mail’ ) deleting the entire subtree rooted by ’mail’
Chapter 11 { File-System Interface Operating System Concepts 29
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Directory and Disk Structure
Acyclic-Graph Directories |Have shared subdirectories and files
list all w count words list
list rade w7
count
root dict spell
Chapter 11 { File-System Interface Operating System Concepts 30
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Directory and Disk Structure
Acyclic-Graph Directories (Cont.)
Two different names (aliasing)
If dict deletes list ) dangling pointer
Solutions:
Backpointers, so we can delete all pointers |Variable size
records a problem
Backpointers using a daisy chain organization
Entry-hold-count solution
New directory entry type
Link { another name (pointer) to an existing file
Resolve the link { follow pointer to locate the file
Chapter 11 { File-System Interface Operating System Concepts 31
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Directory and Disk Structure
General Graph Directory
text mail
avi count unhex hex
count book book mail unhex hyp
root avi tc jim
Chapter 11 { File-System Interface Operating System Concepts 32
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Directory and Disk Structure
General Graph Directory (Cont.)
How do we guarantee no cycles?
Allow only links to file not subdirectories
Garbage collection
Every time a new link is added use a cycle detection algorithm
to determine whether it is OK
Chapter 11 { File-System Interface Operating System Concepts 33
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 Which of the following is true of the tree-structured directory
structure?
A. Users cannot create their own subdirectories.
B. Users cannot acquire permission to access the files of other
users.
C. Directories can share subdirectories and files.
D. It is the most common directory structure.
Answer:
Chapter 11 { File-System Interface Operating System Concepts 34
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 Which of the following is true of the tree-structured directory
structure?
A. Users cannot create their own subdirectories.
B. Users cannot acquire permission to access the files of other
users.
C. Directories can share subdirectories and files.
D. It is the most common directory structure.
Answer: D
Chapter 11 { File-System Interface Operating System Concepts 34
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 Which of the following is true of the tree-structured directory
structure?
A. Users cannot create their own subdirectories.
B. Users cannot acquire permission to access the files of other
users.
C. Directories can share subdirectories and files.
D. It is the most common directory structure.
Answer: D
2 An acyclic-graph directory structure .
A. does not allow the sharing of files.
B. allows the sharing of subdirectories and files.
C. is less complicated than a simple tree-structured directory
structure.
D. is less flexible than a simple tree-structured directory structure.
Answer:
Chapter 11 { File-System Interface Operating System Concepts 34
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 Which of the following is true of the tree-structured directory
structure?
A. Users cannot create their own subdirectories.
B. Users cannot acquire permission to access the files of other
users.
C. Directories can share subdirectories and files.
D. It is the most common directory structure.
Answer: D
2 An acyclic-graph directory structure .
A. does not allow the sharing of files.
B. allows the sharing of subdirectories and files.
C. is less complicated than a simple tree-structured directory
structure.
D. is less flexible than a simple tree-structured directory structure.
Answer: B
Chapter 11 { File-System Interface Operating System Concepts 34
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 The path name /home/people/os-student/chap11.txt is
an example of
A. a relative path name
B. an absolute path name
C. a relative path name to the current directory of /home
D. an invalid path name
Answer:
Chapter 11 { File-System Interface Operating System Concepts 35
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 The path name /home/people/os-student/chap11.txt is
an example of
A. a relative path name
B. an absolute path name
C. a relative path name to the current directory of /home
D. an invalid path name
Answer: B
Chapter 11 { File-System Interface Operating System Concepts 35
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 The path name /home/people/os-student/chap11.txt is
an example of
A. a relative path name
B. an absolute path name
C. a relative path name to the current directory of /home
D. an invalid path name
Answer: B
2 True or False { A relative path name begins at the root.
Answer:
Chapter 11 { File-System Interface Operating System Concepts 35
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 The path name /home/people/os-student/chap11.txt is
an example of
A. a relative path name
B. an absolute path name
C. a relative path name to the current directory of /home
D. an invalid path name
Answer: B
2 True or False { A relative path name begins at the root.
Answer: False
Chapter 11 { File-System Interface Operating System Concepts 35
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 The path name /home/people/os-student/chap11.txt is
an example of
A. a relative path name
B. an absolute path name
C. a relative path name to the current directory of /home
D. an invalid path name
Answer: B
2 True or False { A relative path name begins at the root.
Answer: False
3 True or False { An absolute path name must always begin
at the root.
Answer:
Chapter 11 { File-System Interface Operating System Concepts 35
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 The path name /home/people/os-student/chap11.txt is
an example of
A. a relative path name
B. an absolute path name
C. a relative path name to the current directory of /home
D. an invalid path name
Answer: B
2 True or False { A relative path name begins at the root.
Answer: False
3 True or False { An absolute path name must always begin
at the root.
Answer: True
Chapter 11 { File-System Interface Operating System Concepts 35
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
File-System Mounting
A file system must be mounted before it can be accessed
A unmounted file system (b) is mounted at a mount point
users
/
bill fred
help
sue jane
prog
doc
(a) (b)
Chapter 11 { File-System Interface Operating System Concepts 36
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
File-System Mounting
Mount Point
/
users
sue jane
prog
doc
Chapter 11 { File-System Interface Operating System Concepts 37
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
File Sharing
Sharing of files on multi-user systems is desirable
Sharing may be done through a protection scheme
On distributed systems, files may be shared across a network
Network File System (NFS) is a common distributed
file-sharing method
If multi-user system
User IDs identify users, allowing permissions and protections to
be per-user |Owner of a file/directory
Group IDs allow users to be in groups, permitting group access
rights |Group of a file/directory
Chapter 11 { File-System Interface Operating System Concepts 38
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
File Sharing | Remote File systems
Uses networking to allow file system access between systems
Manually via programs like file transfer protocol (FTP)
Automatically, seamlessly using distributed file systems (DFS)
Semi automatically via the world wide web (WWW)
Client-server model allows clients to mount remote file
systems from servers
Server can serve multiple clients
Client and user-on-client identification is insecure or
complicated
NFS is standard UNIX client-server file sharing protocol
CIFS is standard Windows protocol
Chapter 11 { File-System Interface Operating System Concepts 39
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
File Sharing | Failure Modes
All file systems have failure modes. For example corruption of
directory structures or other non-user data, called metadata
Remote file systems add new failure modes, due to network
failure, server failure
Recovery from failure can involve state information about
status of each remote request
Stateless protocols such as NFS v3 include all information in
each request, allowing easy recovery but less security
Chapter 11 { File-System Interface Operating System Concepts 40
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
File Sharing | Consistency Semantics
How multiple users are to access a shared file simultaneously?
Andrew File System (AFS) implemented complex remote file
sharing semantics
Unix file system (UFS) implements:
Writes to an open file visible immediately to other users of the
same open file
Sharing file pointer to allow multiple users to read and write
concurrently
AFS has session semantics
Writes only visible to sessions starting after the file is closed
Chapter 11 { File-System Interface Operating System Concepts 41
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Protection
File owner/creator should be able to control:
what can be done
by whom
Types of access
Read
Write
Execute
Append
Delete
List
Chapter 11 { File-System Interface Operating System Concepts 42
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Protection | Access Lists and Groups
Mode of access: read, write, execute ) RWX
Three classes of users on Unix/Linux
RWX
(1) owner access 7 ) 1 1 1
(2) group access 6 ) 1 1 0
(3) public access 1 ) 0 0 1
For a particular file (say game) or subdirectory, define an
appropriate access.
Attach a group to a file
chgrp G game
Chapter 11 { File-System Interface Operating System Concepts 43
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Protection | Access Lists and Groups
Windows 7
Access-Control
List Management
Chapter 11 { File-System Interface Operating System Concepts 44
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 The UNIX file system uses which of the following consistency
semantics?
A. Writes to an open file by a user are not visible immediately to
other users that have the file open at the same time.
B. Once a file is closed, the changes made to it are visible only in
sessions starting later.
C. Users are not allowed share the pointer of current location into
the file.
D. Writes to an open file by a user are visible immediately to
other users that have the file open at the same time.
Answer:
Chapter 11 { File-System Interface Operating System Concepts 45
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 The UNIX file system uses which of the following consistency
semantics?
A. Writes to an open file by a user are not visible immediately to
other users that have the file open at the same time.
B. Once a file is closed, the changes made to it are visible only in
sessions starting later.
C. Users are not allowed share the pointer of current location into
the file.
D. Writes to an open file by a user are visible immediately to
other users that have the file open at the same time.
Answer: D
Chapter 11 { File-System Interface Operating System Concepts 45
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 The UNIX file system uses which of the following consistency
semantics?
A. Writes to an open file by a user are not visible immediately to
other users that have the file open at the same time.
B. Once a file is closed, the changes made to it are visible only in
sessions starting later.
C. Users are not allowed share the pointer of current location into
the file.
D. Writes to an open file by a user are visible immediately to
other users that have the file open at the same time.
Answer: D
2 True or False { A file on a Solaris system with permissions
-rwx – -x – -x is an example of both access-control lists as
well as owner/group/universe protection.
Answer:
Chapter 11 { File-System Interface Operating System Concepts 45
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 The UNIX file system uses which of the following consistency
semantics?
A. Writes to an open file by a user are not visible immediately to
other users that have the file open at the same time.
B. Once a file is closed, the changes made to it are visible only in
sessions starting later.
C. Users are not allowed share the pointer of current location into
the file.
D. Writes to an open file by a user are visible immediately to
other users that have the file open at the same time.
Answer: D
2 True or False { A file on a Solaris system with permissions
-rwx – -x – -x is an example of both access-control lists as
well as owner/group/universe protection.
Answer: True
Chapter 11 { File-System Interface Operating System Concepts 45
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 is/are not considered a difficulty when considering file
sharing.
A. Reliability
B. Multiple users
C. Consistency semantics
D. Remote access
Answer:
Chapter 11 { File-System Interface Operating System Concepts 46
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 is/are not considered a difficulty when considering file
sharing.
A. Reliability
B. Multiple users
C. Consistency semantics
D. Remote access
Answer: A
Chapter 11 { File-System Interface Operating System Concepts 46
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 is/are not considered a difficulty when considering file
sharing.
A. Reliability
B. Multiple users
C. Consistency semantics
D. Remote access
Answer: A
2 Which of the following is not considered a classification of
users in connection with each file?
A. owner
B. current user
C. group
D. universe
Answer:
Chapter 11 { File-System Interface Operating System Concepts 46
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
Quick Quiz
1 is/are not considered a difficulty when considering file
sharing.
A. Reliability
B. Multiple users
C. Consistency semantics
D. Remote access
Answer: A
2 Which of the following is not considered a classification of
users in connection with each file?
A. owner
B. current user
C. group
D. universe
Answer: B
Chapter 11 { File-System Interface Operating System Concepts 46
File Concept Access Directory and Disk Structure Mounting File Sharing Protection
End of Chapter 11
Chapter 11 { File-System Interface Operating System Concepts 47