为什么在Linux上实现一个简单的shell命令时会收到错误消息

Question

在Linux Ubuntu 20.04.4中，我在；sh.c"文件进入

./a.out 

命令逐行正常运行。在此处输入图像描述

ls > y
cat < y | sort | uniq | wc > y1
cat y1
rm y1
ls | sort | uniq | wc
rm y

但是，如果将命令保存到"；t.sh"；文件在此处输入图像描述并像一样立即运行它们

./a.out < t.sh 

出现错误。在此处输入图像描述

打印结果：

5 5 29
5 5 29
cat: y1: No such file or directory
rm: Cannot erase 'y1': no such file or directory
4 4 27
rm: Cannot clear 'y': no such file or directory

当我用"；ls〃；命令，cat和rm命令都运行良好，但我收到了这样的错误消息"rm:无法擦除"y1"：没有这样的文件或目录">

怎么了？另一个人使用相同的代码正常工作。。。

这是实现的代码的一部分。

void runcmd(struct cmd *cmd)
{
int p[2], r;
int fd;
int pid;
char str[30] ="/bin/";
FILE * stream;
struct execcmd *ecmd;
struct pipecmd *pcmd;
struct redircmd *rcmd;
if(cmd == 0)
_exit(0);
switch(cmd->type){
default:
fprintf(stderr, "unknown runcmdn");
_exit(-1);
case ' ':
ecmd = (struct execcmd*)cmd;
if(ecmd->argv[0] == 0){
_exit(0);
fprintf(stderr, "exec not implementedn");
}
// Your code here ...
else if(execvp(ecmd->argv[0],ecmd->argv)==-1){
ecmd->argv[0] = strcat(str,ecmd->argv[0]);

if(execvp(ecmd->argv[0],ecmd->argv)==-1){       
fprintf(stderr,"file not foundn");
exit(1);
}

}
break;
case '>':
rcmd = (struct redircmd*)cmd;
ecmd = (struct execcmd*)(rcmd->cmd);
if(0 <(fd = open(rcmd->file,O_CREAT|O_WRONLY,0644))){ 
stream = freopen(rcmd->file,"w",stdout);
runcmd(rcmd->cmd); 
fclose(stream);
}
else {
fprintf(stderr,"file open errorn");
}
close(fd);
stream = NULL;  
break;
case '<':
rcmd = (struct redircmd*)cmd;
// Your code here ...
if( 0 < (fd = open(rcmd->file,rcmd->flags))){
stream = freopen(rcmd->file,"r",stdin);
runcmd(rcmd->cmd);
fclose(stream);
close(fd);
}
else fprintf(stderr,"file open errorn");
break;
case '|':
pcmd = (struct pipecmd*)cmd;
// Your code here ...
struct cmd * lcmd =(pcmd->left);
struct cmd * rcmd =(pcmd->right);
int fd[2];
if(pipe(fd)==-1){ 
fprintf(stderr,"pipe error");
exit(1);
}
pid = fork1(); 
if(pid == 0){ 
dup2(fd[1],1); 
close(fd[0]);  
runcmd(lcmd); 
}
else{ 
dup2(fd[0],0); 
close(fd[1]); 
runcmd(rcmd);
}

break;
}    
_exit(0);
}

Answer 1

您已声明#/脚本顶部的bin.sh