Explanation: kill system call behaves in an identical manner to the kill command. kill sends a signal but doesn’t necessarily kill a process.

Explanation: kill sends a signal but doesn’t necessarily kill a process. Kill system call is used by the library function raise to send any signal to the current process.

Explanation: The alarm call is used to set a timer that generates the SIGALRM signal after the timeout period.

Explanation: If two users execute the same program then memory requirements are not doubled, the text segment in the virtual address space is shared.

Explanation: We say that the address space of a process is virtual because the address specified in the executable doesn’t point to the actual memory location. The virtual addresses are translated into a physical address at runtime by memory management unit (MMU).

Explanation: dup, dup2, fcntl and pipe are the system calls which returns one or more file descriptors when invoked.

Explanation: The environment variables transmitted from parent process to child are available in environ[ ] variable.

Explanation: The environment variables transmitted from parent process to child are available in environ[ ] variable. POSIX specifies two functions, getenv and setenv to obtain and set these values.

Explanation: How a process responds to a signal depends on how things are set up in the program representing the process. However, there are mainly three actions that a program can take upon receiving a signal i.e. ignore the signal and continue execution normally, terminate the process, suspend (stop) the program.

Explanation: The action that a signal takes on receipt of a signal is called disposition. The default disposition of most signals is to terminate the process.