Wait System Call

A call to wait( ) blocks the calling process until one of its child processes exits or a signal is received. After child process terminates, parent continues its execution after wait system call instruction. Child process may terminate due to any of these: It calls exit( ); It returns (an int) from main It receives …

Orphan Process

A process whose parent process no more exists i.e. either finished or terminated without waiting for its child process to terminate is called an orphan process.  In the following code, parent finishes execution and exits while the child process is still executing and is called an orphan process now. However, the orphan process is soon …

fork()

Fork system call use for creates a new process, which is called child process, which runs concurrently with process (which process called system call fork) and this process is called parent process. After a new child process created, both processes will execute the next instruction following the fork() system call. A child process use same …

Shell Programming : Switch Case

Shell Programming : Switch Case Aim To write shell programs using case construct to match patterns. The case statement is used to compare a variables value against a set of constants (integer, character, string, range). If it matches a constant, then the set of statements followed after) is executed till a ; ; is encountered. …

Shell Programming : Loops

Shell Programming : Loops Aim To write shell programs using different types of loops. Shell supports a set of loops such as for, while and until to execute a set of statements repeatedly. The body of the loop is contained between do and done statement. for loop : Method 1: Bash For Loop using “in” …