sh.c (1323B)
1 #include <libc.h> 2 3 #define msg_clear "\033[2J\033[H" 4 5 #define max_line 256 6 #define max_args 16 7 #define max_cwd 256 8 9 static char prompt[] = "; "; 10 11 void execcd(const char *path) { 12 chdir(path); 13 } 14 15 int main(void) { 16 char line[max_line]; 17 char *argv[max_args]; 18 19 while (1) { 20 write(stdout, prompt, 2); 21 22 ssize_t n = read(stdin, line, max_line - 1); 23 if (n <= 0) continue; 24 25 line[n] = '\0'; 26 if (line[n - 1] == '\n') line[n - 1] = '\0'; 27 28 if (strlen(line) == 0) continue; 29 30 if (strcmp(line, "clear") == 0) { 31 write(stdout, msg_clear, strlen(msg_clear)); 32 continue; 33 } 34 35 if (strcmp(line, "exit") == 0) { 36 break; 37 } 38 39 int argc = 0; 40 char *token = strtok(line, " "); 41 while (token != NULL && argc < max_args - 1) { 42 argv[argc++] = token; 43 token = strtok(NULL, " "); 44 } 45 argv[argc] = NULL; 46 47 if (argc == 0) continue; 48 49 if (strcmp(line, "cd") == 0) { 50 execcd(argv[1]); 51 continue; 52 } 53 54 int pid = fork(); 55 if (pid == 0) { 56 /* child */ 57 execvp(argv[0], argv); 58 59 write(stderr, "sh: command not found: ", 23); 60 write(stderr, argv[0], strlen(argv[0])); 61 write(stderr, "\n", 1); 62 exit(127); 63 } else if (pid > 0) { 64 /* parent */ 65 int status; 66 waitpid(pid, &status, 0); 67 } 68 } 69 return 0; 70 }