Process Programming

Question 1

ps vs ps aux

Answer 1

ps returns processes of current terminal while ps aux returns all processes of the user

Question 2

kill -9 pid

Answer 2

SIGKIL to process with pid. SIGKILL can not be handle. Its like “force kill”

Question 3

Το παιδι κληρονομει τις μεταβλητες του πατερα του;

Answer 3

Ναι

Question 4

What is orphan process?

Answer 4

A process whose parent has terminated or exited

Question 5

What is zombie process?

Answer 5

A process that has terminated remains in the system until its parent receives its exit code. This whole time the process is a zombie.

Question 6

In the exec family whats the use of “l” and whats the use of “v”

Answer 6

“l” is used when the arguments to the new process are fixed and is called like:
execl(path, arg1,arg2,arg3)
“v” is used then the arguments are variable and they are passed as a list like:
execv(path, args[])

Question 7

In the exec family whats the use of “e”

Answer 7

With “e” we can define an environment for the child process (environment variables). For example:
execle(parth,arg1,arg2,env)
env should be a mapping (dictionary) with key:value pairs –> env_var:value

Question 8

In the exec family whats the use of “p”

Answer 8

When “p” is used, the PATH env var is used to locate the file to be executed. If “p” is not used then an absolute or relative path must be provided for example:

execlp(filename, arg1, arg2)
execl(absolute or relative path, arg1,arg2)

Question 9

Κληρονομουνται οι file descriptors?

Answer 9

Ναι

Question 10

In a pipe which is the read and which the write end?

Answer 10

p[0] is read
p[1] is write