1 #include <unistd.h>
2
3 #include <stdio.h>
4 #include <stdlib.h>
5 #include <string.h>
6
7 #define CMDSIZE 4096
8
9 static void prompt(void)
10 {
11 printf("[mysh]$ ");
12 fflush(stdout);
13 }
14
15 static void getcmd(char *cmd, char **argv)
16 {
17 int i = 0;
18
19 fgets(cmd, CMDSIZE, stdin);
20
21 argv[i] = strtok(cmd, " \t\n");
22 for (i++; argv[i - 1] != NULL; i++) {
23 argv[i] = strtok(NULL, " \t\n");
24 }
25 }
26
27 static void myexit(char **argv)
28 {
29 exit(0);
30 }
31
32 static void mycd(char **argv)
33 {
34 chdir(argv[1]);
35 }
36
37 #define NAMESIZE 256
38 struct {
39 void (*func)(char **);
40 char name[NAMESIZE];
41 } internal_list[] = {
42 {myexit, "exit"},
43 {mycd, "cd"},
44 {NULL, },
45 };
46
47 static int internal_ind(const char *name)
48 {
49 int i;
50
51 for (i = 0; internal_list[i].func != NULL; i++) {
52 if (strcmp(name, internal_list[i].name) == 0) {
53 return i;
54 }
55 }
56 return -1;
57 }
58
59 int main(void)
60 {
61 char cmd[CMDSIZE];
62 char *argv[CMDSIZE / 2];
63 pid_t pid;
64 int ind;
65
66 while (1) {
67 prompt();
68
69 getcmd(cmd, argv);
70 if ((ind = internal_ind(argv[0])) != -1) {
71 internal_list[ind].func(argv);
72 } else {
73 pid = fork();
74 /* if error */
75 if (pid == 0) {
76 execvp(argv[0], argv);
77 perror(argv[0]);
78 exit(1);
79 }
80 wait(NULL);
81 }
82 }
83
84 return 0;
85 }
