用C语言编写一个Linux下的简单shell程序

这是一个简单的C程序，展示了如何进行系统调用执行logout cd ls pwd pid rm mkdir mv cp等命令，这是一个简单的命令解释程序shell，其源代码如下：

#include <stdio.h> #include <string.h> #include <unistd.h> #include <stdlib.h> #include <sys/types.h> #include <errno.h> #include <sys/stat.h> char parsecmd(char *); /************关于本文档******************************************** *filename:用C语言编写一个Linux下的简单shell程序 *purpose:展示了C语言如何进行系统调用执行logout cd ls pwd pid rm mkdir mv cp等命令 *wrote by: zhoulifa([e-mail]) 周立发(http://zhoulifa.bokee.com) Linux爱好者 Linux知识传播者 SOHO族 开发者 最擅长C语言编程 *date time:2006-07-16 15:00:00 *Note: 任何人可以任意复制代码并运用这些文档，当然包括你的商业用途 * 但请遵循GPL。 *Hope:希望越来越多的人贡献自己的力量，为科学技术发展出力 *********************************************************************/ int main(int argc, char ** argv) {   char cmd[1024];   char tmp[101];   char b = 'F';   char * p;   while(1) {     memset(cmd, 0, 1024);     printf("Next command%% ");/*显示提示信息*/     fgets(cmd, 1000, stdin);/*接受用户输入，命令最长1000个字符*/     cmd[strlen(cmd) - 1] = 0;/*去掉输入的回车符*/     b = parsecmd(cmd);/*分析取得用户命令字*/     if(b=='T') break;/*如果是logout就退出程序*/     switch(b){     case 1:/*切换工作目录*/       if(chdir(cmd + 3) != 0) {         printf("chdir(%s) error!%s\n", cmd + 3, strerror(errno));       }       printf("I'm working in '%s' now\n", getcwd(tmp, 100));       break;     case 2:/*ls命令*/     case 7:/*cp命令*/     case 8:/*pwd命令*/       system(cmd);       break;     case 3:/*pid命令*/       printf("%d\n", getpid());       break;     case 4:/*rm命令*/       remove(cmd + 3);       break;     case 5:/*mkdir命令*/       mkdir(cmd + 6, 0755);       break;     case 6:/*mv命令*/       p = strchr(cmd + 3, ' ');       *p = 0;       rename(cmd + 3, p + 1);       break;     case 0:/*不能识别的命令*/       printf("Bad command, try again! All aviable commands are:\nlogout cd ls pwd pid rm mkdir mv cp\n", getpid());       break;     }   } } char parsecmd(char * s) {   if(!strcasecmp(s, "logout")) return 'T';   else if(!strncasecmp(s, "cd", 2)) return 1;   else if(!strncasecmp(s, "ls", 2)) return 2;   else if(!strncasecmp(s, "pwd", 3)) return 8;   else if(!strncasecmp(s, "pid", 3)) return 3;   else if(!strncasecmp(s, "rm", 2)) return 4;   else if(!strncasecmp(s, "mkdir", 5)) return 5;   else if(!strncasecmp(s, "mv", 2)) return 6;   else if(!strncasecmp(s, "cp", 2)) return 7;   else return 0; }

命令运行结下：

Next command% ls / bin   cdrom  dev  home    initrd.img  lost+found  mnt  proc  sbin  sys  usr  vmlinuz boot  data   etc  initrd  lib         media       opt  root  srv   tmp  var Next command% pwd /data/example/c Next command% cd / I'm working in '/' now Next command% pwd / Next command% cd /tmp I'm working in '/tmp' now Next command% pwd /tmp Next command% ls gconfd-administrator  ksocket-administrator  plugtmp                                   ssh-MmlTLh5149 gconfd-root           mapping-administrator  scim-helper-manager-socket-administrator  virtual-administrator.XSmKSv kde-administrator     orbit-administrator    scim-panel-socket:1-administrator keyring-g5rmCS        orbit-root             scim-socket-frontend-administrator Next command% mkdir xxxx Next command% ls gconfd-administrator  ksocket-administrator  plugtmp                                   ssh-MmlTLh5149 gconfd-root           mapping-administrator  scim-helper-manager-socket-administrator  virtual-administrator.XSmKSv kde-administrator     orbit-administrator    scim-panel-socket:1-administrator         xxxx keyring-g5rmCS        orbit-root             scim-socket-frontend-administrator Next command% rm xxxx Next command% ls gconfd-administrator  ksocket-administrator  plugtmp                                   ssh-MmlTLh5149 gconfd-root           mapping-administrator  scim-helper-manager-socket-administrator  virtual-administrator.XSmKSv kde-administrator     orbit-administrator    scim-panel-socket:1-administrator keyring-g5rmCS        orbit-root             scim-socket-frontend-administrator ? Next command% logout