/*-----------------------------------------------------------------*/
/* This file is modified based on /
/ http://www.csl.mtu.edu/cs4411.ck/www/NOTES/process/fork/shell.c /
/ Enjoy your learning. Good luck. /

/-----------------------------------------------------------------*/

#include
#include
#include

void parse(char line, char **argv)
{
while (*line != '\0') { / if not the end of line ....... /
while (*line == ' ' || *line == '\t' || *line == '\n')
*line++ = '\0'; / replace white spaces with 0 /
*argv++ = line; / save the argument position /
while (*line != '\0' && *line != ' ' &&
*line != '\t' && *line != '\n')
line++; / skip the argument until ... /
}
*argv = '\0'; / mark the end of argument list */
}

void execute(char **argv)
{
pid_t pid;
int status;

 if ((pid = fork()) < 0) {     /* fork a child process           */
      printf("*** ERROR: forking child process failed\n");
      exit(1);
 }
 else if (pid == 0) {          /* for the child process:         */
      if (execvp(*argv, argv) < 0) {     /* execute the command  */
           printf("*** ERROR: exec failed\n");
           exit(1);
      }
 }
 else {                                  /* for the parent:      */
      while (wait(&status) != pid);       /* wait for completion  */

;
}
}

void main(void)
{
char *argv[60];
FILE *fp;
fp = fopen("a.txt","r");
char * line = NULL;
size_t len = 0;
ssize_t read;
while ((read = getline(&line, &len, fp)) != -1)
{
printf("bash: %s", line);
line[read -1]='\0';
parse(line, argv);
execute(argv);
}

}

写了指令的文件放在同一目录下