Hargobind Atwal

ex1/ex1.c

@@ -5,10 +5,36 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <sys/types.h>
+#include <unistd.h>
 
 int main(void)
 {
     // Your code here
+    int *x = malloc(sizeof(int));
+    pid_t pid = fork();
+    (*x)++;
+    if (pid == 0)
+    {
+        printf("%d Child proccess 1 %d\n", *x, pid);
+        (*x)++;
+        printf("%d Child proccess 2 %d\n", *x, pid);
+
+        execlp("ls", "ls", NULL);
+        perror("exec");
 
+        (*x)++;
+        printf("%d Child proccess 3 %d\n", *x, pid);
+        // exit(1);
+    }
+    else
+    {
+        printf("%d Parent processes 1 %d\n", *x, pid);
+        (*x)++;
+        printf("%d Parent processes 2 %d\n", *x, pid);
+        waitpid(pid, 1, 1);
+        (*x)++;
+        printf("%d Parent processes 3 %d\n", *x, pid);
+    }
     return 0;
 }

ex2/ex2.c

@@ -5,10 +5,63 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
 
 int main(void)
 {
     // Your code here 
+
+    // open file
+    FILE * fp = fopen("text.txt", "w+");
+    if (!fp) {
+        perror("File opening failed");
+        return EXIT_FAILURE;
+    }
+    mkdir("subdir", 0755);
+
+
+    // read file loop
+    int c;
+    while((c = fgetc(fp)) != EOF) 
+    {
+        putchar(c);
+    }
+
+    // writing to file from parent and child process
+
+    fprintf(fp, "this came from the program\n");
+
+    pid_t pid = fork();
+    if (pid == 0) // Child process
+    {
+
+    fprintf(fp, "this came from the Child process\n");
+    // fwrite(fp, "some stuff from child\n");
+    }
+    else          // Parrent process
+    {
+    wait(NULL);
+    // fwrite(fp, "some stuff from parent\n");
+    fprintf(fp, "this came from the Parent process\n");
+
+    }
+
+    char buff[128] = {0};
+
+    // fgets(buff, 128, fp);
+    read(fp, buff, 100);
+
+    printf("Buffer has: \"%s\n\"", buff);
+
+
+    if (ferror(fp))
+        puts("I/O error when reading");
+    else if (feof(fp))
+        puts("End of file reached successfully");
+
+    fclose(fp);
+
 
     return 0;
 }

ex3/ex3.c

@@ -11,5 +11,18 @@ int main(void)
 {
     // Your code here
 
+    pid_t pid = fork();
+    if (pid == 0) // Child process
+    {
+        printf("Hello\n");
+    }
+    else          // Parrent process
+    {
+        wait(NULL);
+        printf("goodbye\n");
+
+    }
+
+
     return 0;
 }

ex4/ex4.c

@@ -10,7 +10,25 @@
 
 int main(void)
 {
-    // Your code here    
+    // Your code here
 
+    printf("starting program\n");
+    printf("%s", "hello");
+    exec("/bin/ls", "ls", NULL);
+    printf("ran ls\n");
+
+    execlp("/bin/ls", "ls", NULL);
+    pid_t  pid = fork();
+    if (pid == 0) // child process
+    {
+        execle("/bin/cd ex4", "cd", NULL);
+        execle("/bin/ls", "ls", NULL);
+        // exec("/bin/ls");
+    }
+    else         // parent process
+    {
+        execle("/bin/ls", "ls", NULL);
+
+    }
     return 0;
 }

ex5/ex5.c

@@ -9,14 +9,54 @@
 #include <sys/wait.h>
 
 #define MSGSIZE 16
-
+#define BUFF_SIZE 128
 char* msg1 = "hello world #1";
 char* msg2 = "hello world #2";
 char* msg3 = "hello world #3";
 
-int main(void)
+int main(int argc, char * argv[])
 {
     // Your code here
-
+
+    char buf[128];
+
+    // fd[0] READ end of the pipe 
+    // fd[1] WRITE end of the pipe
+    int fd[2]; // file descriptor
+
+    pipe(fd);
+
+    if (!fork()) { // child process
+        close(1);
+        dup(fd[1]);
+        close(fd[0]);
+        printf("yooooo");
+        write(fd[1], msg1, MSGSIZE);
+        write(fd[1], msg2, MSGSIZE);
+        write(fd[1], msg3, MSGSIZE);
+    } else {     // parent process
+        close(0);
+        dup(fd[0]);
+        close(fd[1]);
+        char read_buf[100];
+        read(fd[0], read_buf, MSGSIZE);
+        printf("\"%s\" \n", read_buf);
+        read(fd[0], read_buf, MSGSIZE);
+        printf("\"%s\" \n", read_buf);
+        read(fd[0], read_buf, MSGSIZE);
+        printf("\"%s\" \n", read_buf);
+    }
+
+    // char inBuff[BUFF_SIZE];
+    // char aBuff[BUFF_SIZE];
+    // // fgets(aBuff, BUFF_SIZE, fd[0]);
+
+    // int bytes_written = write(fd[1], "We come in peace\n", 17);
+
+    // int bytes_read = read(fd[0], buf, sizeof(buf));
+
+    // // write(STDOUT_FILENO, aBuff, bytes_read);
+    // write(STDOUT_FILENO, buf, bytes_read);
+
     return 0;
-}
+}

ex5/pipe3.c

@@ -0,0 +1,29 @@
+/*
+** pipe3.c -- a smartest pipe example
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int main(void)
+{
+	int pfds[2];
+
+	pipe(pfds);
+
+	if (!fork()) {
+		close(1);       /* close normal stdout */
+		dup(pfds[1]);   /* make stdout same as pfds[1] */
+		close(pfds[0]); /* we don't need this */
+		execlp("ls", "ls", NULL);
+	} else {
+		close(0);       /* close normal stdin */
+		dup(pfds[0]);   /* make stdin same as pfds[0] */
+		close(pfds[1]); /* we don't need this */
+		execlp("wc", "wc", "-l", NULL);
+	}
+
+	return 0;
+}
+

ex6/ex6.c

@@ -14,13 +14,33 @@ and `clock_gettime()` should work just fine.
 #include <stdio.h>
 #include <unistd.h>
 #include <time.h>
+#include <stdint.h>	/* for uint64 definition */
 
 #define number_iter 1000000
 #define BILLION 1000000000L
 
+// struct timespec {
+// 	time_t   tv_sec;        /* seconds */
+// 	long     tv_nsec;       /* nanoseconds */
+// };
+
+
 int main()
 {
+    uint64_t diff;
+    struct timespec start, end;
+    int i;
+
     // Your code here
+    int start_time = clock_gettime(CLOCK_MONOTONIC, &start);
+
+    // sleep(2);
+    char buf[128] = "wasup...\n";
+    write(1, buf, 9);
+
+    int end_time = clock_gettime(CLOCK_MONOTONIC, &end);
+    diff = BILLION * (end.tv_sec - start.tv_sec) + end.tv_nsec - start.tv_nsec;
+    printf("program ran for %llu \n",(long long unsigned int) diff);
 
     return 0;
 }

runner.sh

@@ -0,0 +1,2 @@
+#gcc $1/$1.c -o $1/$1 && ./$1/$1
+nodemon -w $1/$1.c --exec "gcc $1/$1.c -o $1/$1 && ./$1/$1"