CS 3377 Dollinger UNIX Exam 2

when a program starts, what are the three standard file descriptors that are open and ready for use? (only need to know that there are three)

1. stdin

2. stdout

3. stderr

gives you a freopen, know what it does

- reopens a file with a different mode

- freopen works on streams

what are the four areas in the c++ programming memory model?

1. stack

2. heap

3. bss

4. uninitialized data area

which one of the four segments of the program lasts the lifetime of the program unless your application deletes it?

heap

in the c++ program memory model, what contains variables that are explicitly initialized in the program?

initialized data segment

in the c++ programming memory model, data in this memory area is initialized by the kernel to arithmetic 0 until the programs stops executing

uninitialized data segment

in the c++ programming memory model, what memory area stores information that is saved each time a function is called? and each time a function is called, the address the word will return to any arguments.

stack

in the c++ memory model, what's the memory area that does dynamic memory allocation?

heap

what part of the memory consists of the machine instructions that the cpu executes?

text segment

what's stored in the BSS (know what the bss is -> text segment?)

static variables

where's dynamic memory done?

heap

in the c++ programming memory model, the uninitialized memory area variables have a lifetime of the program. (t/f)

true

after a fork, identify the differences b/t a parent and a child

both parent and child have different processes and different return values(?) check this

what's the return value of a fork for the child?

0

what does a fork return if it fails?

-1

including the initial parent process, the total number of parent processes after a fork executes will be how many?

2

gives you programs using forks and couts, will ask you how many lines are outputted.

2

after you execute a fork, and you get the pid and cout it, what value will be displayed?

you don't know (trick question)

which of the following is NOT true about a fork?

forks split the input data into multiple parts

after a fork operation, the pid of the parent process is always 0 (t/f)

false

what allows you to make more than one file descriptor entry point to the same file entry?

dup() -> not an option, so fork?

for pipes, what's the index used to read?

fds 0

for pipes, what's the index used to write?

fds 1

what is NOT true about pipes?

the pipe API is used to create a pipe between 2 programs

can you do pipes between two existing processes? (y/n)

no

when we use name pipes, the correct open will block until the corresponding open will open the pipe (t/f)

true

when using name pipes, both the client and the server must use known name pipes to establish communication (t/f)

true

what's the sequence of operations for doing pipes?

(CMCO)

1. create

2. mkfifo

3. chmod

4. open

what's the correct order of operations in a client-server?

(SCRW)

1. socket

2. connect

3. read

4. write

what's the correct order of operations in a socket server?

(SBLARW)

1. socket

2. bind

3. listen

4. accept

5. read/write

for the socket client, what do both programs must have to know to communicate?

port number

for a socket client and server, both programs must know the port address to communicate with each other (t/f)

true

which api is NOT used with a client socket?

a. listen

b. socket

c. read

d. connect

e. write

listen

what is the interface of the ipc mechanism that can occur between systems across the network?

sockets

on the server side, is there a connect operation? (y/n)

no

can sockets communicate between processes on the same machine? (y/n)

yes, with address 127.0.0.1

when setting up the socket call, we specified SOCK_STREAM. what does SOCK_STREAM indicate?

TCP ip

pthread create only takes one argument for its last parameter (t/f)

true

if i do a pthread create, it'll set up a thread configuration and it then must do a pthread start command (t/f)

false, there is no pthread start

a process by default is only one thread of control, one set of machine instructions executing at a time (t/f)

true

in a linux system, to correctly build a c++ application that uses pthreads, #include pthread.h must exist in the source code and a -pthread must be included in the g++ build line (t/f)

true

which memory segment is not shared by multiple threads of a program?

stack

threads improve program performance because threads in the process can execute for times greater than the time allocated for the process of the thread (t/f)

false

we lock and unlock the mutex to set up a critical code section. what does it do to the threads?

only lets one thread in at a time

what's the operation we use to lock and unlock the critical code section?

mutex

cout's are NOT thread safe (t/f)

true

in the main program thread, what waits for a starter thread to complete?

pthread_join

what's not true about threads?

threads are created by fork() system calls

linux is what type of operating system?

pre-emptive and time-shared

execvp() makes a mirror copy of a process? (t/f)

false

gives code segments and asks a couple questions about how many total processes there are