Signals ======== – A signal is an event generated by UNIX/LINUX system in response to some condition. – On receipt of a signal, process may in turn take some action. – Signals are generated by some error conditions such as:- … Continue reading
Replacing a Process Image ========================= – The exec function replaces current process with a new process. – The path of new process is specified as argument to exec. – It is defined in header : #include<unistd.h> – Last argument of … Continue reading
Orphan Process =============== If in a process, the parent process is terminated before the child process, the child process become orphan – It takes the lowest possible process as its parent – And its PPID is changed to the PID … Continue reading
Zombie or Defunct Process ========================== If a child proces tries to teminate,its association with parent remains until the parent terminates normally or calls wait. – The child process entry in process table is therfore not freed up immediately. – Althougth … Continue reading
Waiting For a Process ===================== – Sometime we would like to find out when a child process has finished. – It is needed for parent process to wait until the child finishes before continuing by calling wait. – It has … Continue reading
Process Duplication using system call fork ============================== – A new process is created using fork(). – fork() is a system call. – fork duplicates the current process. – It creates a new entry in the process table with many of … Continue reading
Types of Inter-process Communications (IPCs) in Linux : 1. Pipes 2. Named Pipes/FIFO 3. Signals 4. Semaphores 5. Message Queue 6. Shared Memory
PCB (Process Control Board) ———————————- Every Process has its Process Control Board(PCB) which tells about the process. PCB contains PID,PPID,PC(program counter),nice value of process. PID :- * PID is Process Identification of any process. * It is a number . … Continue reading
if we simply pass the address of local variable to a thread function then when that function ends then address of that variable lost(if variable is automatic) and we try to access that address or variable the it doesn’t give … Continue reading