原创 第七章——进程环境

      1 #include <stdio.h>
      2
      3 main()
      4 {
      5         printf("Hello world.\n");
      6 }

yannzi@ubuntu:~/桌面/_7$ cc hello.c
yannzi@ubuntu:~/桌面/_7$ ./a.out
Hello world.
yannzi@ubuntu:~/桌面/_7$ echo $?
13
yannzi@ubuntu:~/桌面/_7$ cc -std=c99 hello.c
hello.c:4: 警告： 返回类型默认为‘int’
yannzi@ubuntu:~/桌面/_7$ ./a.out
Hello world.
yannzi@ubuntu:~/桌面/_7$ echo $?
0


      1 #include "apue.h"
      2
      3 static void my_exit1(void);
      4 static void my_exit2(void);
      5
      6 int main()
      7 {
      8         if (atexit(my_exit2) != 0)
      9                 printf("can't register my_exit2");
     10         if (atexit(my_exit1) != 0)
     11                 printf("can't register my_exit1");
     12         if (atexit(my_exit1) != 0)
     13                 printf("can't register my_exit1");
     14         printf("main is done\n");
     15         return 0;
     16 }
     17
     18 static void
     19 my_exit1()
     20 {
     21         printf("first exit handler\n");
     22 }
     23
     24 static void
     25 my_exit2()
     26 {
     27         printf("second exit handler\n");
     28 }

yannzi@ubuntu:~/桌面/_7$ gcc -o stop_to_process_program stop_to_process_program.
c
yannzi@ubuntu:~/桌面/_7$ ./stop_to_process_program
main is done
first exit handler
first exit handler
second exit handler

      1 #include "apue.h"
      2
      3 int
      4 main(int argc, char *argv[])
      5 {
      6         int i;
      7
      8         for (i = 0; i < argc; i++)      //echo all command-line args
      9                 printf("argv[%d]: %s\n", i, argv);
     10         exit(0);
     11 }


yannzi@ubuntu:~/桌面/_7$ gcc -o echo_all_command_line_args_7_3 echo_all_command_
line_args_7_3.c
yannzi@ubuntu:~/桌面/_7$ ./echo_all_command_line_args_7_3
argv[0]: ./echo_all_command_line_args_7_3
yannzi@ubuntu:~/桌面/_7$ ./echo_all_command_line_args_7_3 arg1 TEST foo
argv[0]: ./echo_all_command_line_args_7_3
argv[1]: arg1
argv[2]: TEST
argv[3]: foo

共享库
cc -static ／／阻止gcc使用共享库

setjmp和longjmp函数