IPC using Pipes

Pipes/CMakeLists.txt

@@ -18,6 +18,7 @@ set(CMAKE_CXX_EXTENSIONS        OFF)
 # Add source to this project's executable.
 add_executable (Pipes_demo "Pipes_demo.c" )
 add_executable (2ProcessPipes "2ProcessPipes.c")
+add_executable (Challenge "Challenge.c")
 
 
 

Pipes/Challenge.c

@@ -0,0 +1,40 @@
+/*
+	To implement "ls | wc -l" in C.
+	This only work in linux system.
+*/
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int main(int argc, char* argv[]) {
+
+	int pfds[2];
+
+	pipe(pfds);
+
+	/*
+		dup(int fd) : it duplicates the specified fd to the free fd value with lowest
+				numeric value.
+	*/
+
+	if (!fork()) {
+
+		close(1); /* closing the stdout whose fd value is 1 for a process. */
+		dup(pfds[1]); /* setting the stdout of process to writing end of the pipe. */
+		close(pfds[0]); /* Reading end of the pipe is not needed by the child process. */
+		execlp("ls", "ls", NULL);
+	}
+	else {
+
+		close(0); /* closing the stdin whose fd value 0 for a process. */
+		dup(pfds[0]); /* setting the stdin of process to reading end of the pipe. */
+		close(pfds[1]); /* Writing end of the pipe is not needed by the parent process. */
+		execlp("wc", "wc", "-l", NULL);
+
+	}
+
+
+	return 0;
+}