8 finished.

8/fork/echoarg.c

@@ -0,0 +1,8 @@
+#include <stdio.h>
+
+int main(int argc, char *argv[]) {
+  for(int i = 0; i < argc; i++) {
+    printf("Arg[%d] = %s\n", i, argv[i]);
+  }
+  return 0;
+}

8/fork/exec.c

@@ -0,0 +1,10 @@
+#include <unistd.h>
+#include <stdio.h>
+
+int main(void) {
+  printf("exec fork.c -> b.out\n");
+  if(execl("./b.out", NULL) < 0) {
+      printf("execl error\n");
+  }
+  return 0;
+}

8/fork/exec2.c

@@ -0,0 +1,9 @@
+#include <unistd.h>
+#include <stdio.h>
+
+int main(void) {
+  if(execl("./itptfile", "tools", "yeah", ".", NULL) < 0) {
+    printf("exec error\n");
+  }
+  return 0;
+}

8/fork/fork.c

@@ -0,0 +1,29 @@
+#include <unistd.h>
+#include <stdio.h>
+#include <sys/wait.h>
+#include <stdlib.h>
+
+int main(void) {
+  pid_t pid = fork();
+
+  if (pid != 0) {
+    pid_t pidp = getpid();
+    pid_t ppidp = getpid();
+    uid_t uidp = getuid(), euidp = geteuid();
+    gid_t gidp = getgid(), egidp  = getegid();
+    printf("Father Process PID %d PPID %d UID %d EUID %d GID %d EGID %d\n", pidp, ppidp, uidp, euidp, gidp, egidp);
+
+    int status;
+    pid_t pidc = wait(&status);
+    printf("Child Process PID %d Exited, status %d.\n", pidc, status);
+  }
+  else {
+    pid_t pidc = getpid();
+    pid_t ppidc = getpid();
+    uid_t uidc = getuid(), euidc = geteuid();
+    gid_t gidc = getgid(), egidc  = getegid();
+    printf("Child Process PID %d PPID %d UID %d EUID %d GID %d EGID %d\n", pidc, ppidc, uidc, euidc, gidc, egidc);
+    exit(0);
+  }
+  return 0;
+}

8/fork/getlogin.c

@@ -0,0 +1,10 @@
+#include <unistd.h>
+#include <stdio.h>
+
+int main(void) {
+  char *name = getlogin();
+
+  printf("%s\n", name);
+
+  return 0;
+}

8/fork/itptfile

@@ -0,0 +1 @@
+#! /home/eric/test/echoarg foo bar

8/fork/nice.c

@@ -0,0 +1,25 @@
+#include <unistd.h>
+#include <sys/resource.h>
+#include <stdio.h>
+
+int main(void) {
+
+  printf("NZERO: %d\n", sysconf(_SC_NZERO));
+
+  if(nice(16) < 0) {
+    printf("nice error\n");
+    return -1;
+  }
+
+  int prior = getpriority(PRIO_PROCESS, 0);
+
+  if(prior < 0) {
+    printf("getpriority error\n");
+    return -1;
+  }
+
+  printf("priority: %d\n", prior);
+  
+
+  return 0;
+}

8/fork/times.c

@@ -0,0 +1,19 @@
+#include <sys/times.h>
+#include <unistd.h>
+#include <stdio.h>
+
+int main(void) {
+  struct tms buf;
+
+  for(int i = 0, x = 1; i < 1e8; i++) x*=2; 
+
+  if(times(&buf) < 0) {
+    printf("times error\n");
+    return -1;
+  }
+
+  printf("utime: %ld stime: %ld cutime: %ld cstime: %ld\n", buf.tms_utime, buf.tms_cutime, buf.tms_cutime, buf.tms_cstime);
+
+  printf("clk_tck: %d\n", sysconf(_SC_CLK_TCK));
+  return 0;
+}

8/fork/wait.c

@@ -0,0 +1,37 @@
+#include <unistd.h>
+#include <sys/wait.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(void) {
+  pid_t pid = fork();
+
+  if(pid != 0){
+    
+    pid = fork();
+
+    if(pid != 0) {
+      int status;
+      pid_t pidr = waitpid(pid, &status, 0);
+
+      printf("WPID %d %d RTN %d\n", pid, pidr, status);
+      
+      if(WIFEXITED(status)){
+        printf("Child Process Exited Status %d.\n", WEXITSTATUS(status));
+      }
+
+      exit(0);
+
+    }
+    else {
+      printf("CPID: %d\n", getpid());
+      exit(2);
+    }
+
+  }
+  else {
+    printf("CPID: %d\n", getpid());
+    exit(1);  
+  }
+  
+}