ex1 td5

td/td5/ex1.c

@@ -0,0 +1,47 @@
+#include <fcntl.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <assert.h>
+#include <sys/wait.h>
+int main(int argc, char *argv[])
+{
+	pid_t p;
+	int t[2];
+	assert(pipe(t) == 0);
+
+	p = fork();
+
+	if (p == 0){
+		close(t[0]);
+		dup2(t[1],STDOUT_FILENO);
+		close(t[1]);
+		execlp("ls","ls",NULL);
+		assert(0);
+	}
+
+	p = fork();
+
+	if (p == 0){
+		int fd = open("output.txt",O_WRONLY|O_CREAT|O_APPEND,0644);
+		assert(fd != -1);
+
+		close(t[1]);
+		dup2(t[0],STDIN_FILENO);
+		close(t[0]);
+		dup2(fd,STDOUT_FILENO);
+		close(fd);
+		execlp("wc","wc",NULL);
+		assert(0);
+
+	}
+
+	close(t[0]);
+	close(t[1]);
+
+	wait(NULL);
+	wait(NULL);
+
+	return 0;
+}