shell.c

liunx下的shell实现；进程、线程同步的实现；I/O系统调用的比较（mmap）——操作系统的课程设计

 #include<unistd.h>
#include<stdlib.h>
#include<sys/wait.h>
#include<stdio.h>
#include<string.h>

#define P_ID 1
void parse (char *cmdname, char *cmdargv[], char *cmdline);
void execute (char *fiename, char *argv[]);
void cd (char *cmdargv[]);
void environ (char *cmdargv[]);
void echo (char *cmdargv[]);
void help ();
void jobs (char *cmdargv[]);
void quit ();
int
main (int argc,char *argv[])
{
	char cmdname[256] = "";
	char *cmdargv[256]={""};
	char cmdline[256] = "";
	printf ("welcome to use lshell.\n");
	while (1)
	{
	  printf ("%s@%s:%s$ ",getlogin(),"lshell",get_current_dir_name());
	  gets (cmdline);
	  parse (cmdname, cmdargv, cmdline);
	  if (!strcmp (cmdname, "environ"))
	    environ (cmdargv);
	  else if (!strcmp (cmdname, "cd"))
	    chdir(cmdargv[1]);
	  else if (!strcmp (cmdname, "echo"))
	    echo (cmdargv);
	  else if (!strcmp (cmdname, "help"))
	    help ();
	  else if (!strcmp (cmdname, "jobs"))
	    jobs (cmdargv);
	  else if (!strcmp (cmdname, "quit"))
	    quit ();
	  else if (!strcmp (cmdname, "exit"))
	    quit ();
	  else if (!strcmp (cmdname, "bye"))
	    quit ();
	  else
	    execute(cmdname,cmdargv);
	  
	}
}

void
cd (char *cmdargv[])
{
  execute ("cd", cmdargv);
}

void
environ (char *cmdargv[])
{
  execute ("env", cmdargv);
}
void
echo (char *cmdargv[])
{
  execute ("echo", cmdargv);
}

void
help ()
{
printf("\n\t\t********** shell帮助手册**********\n");
 printf("\n\t\t一、本shell支持以下内部命令：\n");
 printf("\t\t(1)cd 目录名，更改当前的工作目录到指定的目录\n");
 printf("\t\t(2)environ,列出所有环境变量字符串的设置，也可使用外部命令env\n");
 printf("\t\t(3)echo 内容，显示echo后的内容且换行\n");
 printf("\t\t(4)help,显示本帮助手册内容\n");
 printf("\t\t(5)jobs,输出当前正在运行的进程，相当于外部命令ps\n");
 printf("\t\t(6)quit,exit,bye,退出shell\n");
 printf("\t\t二、外部命令直接输入即可运行，支持多参数\n");
 printf("\n\t\t*********************************************\n\n");
}
void
jobs (char *cmdargv[])
{
  execute ("ps",cmdargv);
}
void
quit ()
{
  printf ("quit lshell.\n");
  exit (0);
}

void
parse (char *cmdname, char *cmdargv[], char *cmdline)
{
  char *d = " ";
  char *p;
  int i = 0;
  cmdargv[0]= strtok (cmdline, d);
  strcpy (cmdname, cmdargv[0]);
  while ((p = strtok (NULL, d)))
    {
      i++;
      cmdargv[i]= p;
    }
  cmdargv[++i]=NULL;
}

void
execute (char *filename, char *argv[])
{
  pid_t pid;
  if ((pid = fork ()) < 0)
    {
      printf ("fork error\n");
      exit (EXIT_FAILURE);
    }
  else if (pid == 0)
    {
      if (execvp (filename,argv))
	printf ("-lshell: %s: command not found\n",filename);
      exit (EXIT_FAILURE);
    }
  waitpid (pid, 0, 0);
  return;
}