带有系统函数的c程序中的大括号扩展

问题描述

我尝试了命令

cat tmp/file{1..3} >新建文件

并且完美运行

但是当我编译并执行以下c程序时

But when i compile and execute the following c program

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

void main() {
   char command[40];
   int num_of_points = 3;
   sprintf(command,"cat tmp/file{1..%d} > file.Ver",num_of_points);
   system(command);
}

消息

cat: tmp/file{1..3}: No such file or directory

出现

好像系统没有做大括号扩展

It seems like system does not make brace expansion

推荐答案

问题是system()调用的shell，不是Bash，而是另一个不支持大括号扩展的shell.

The problem is the shell invoked by system(), it is not Bash, but another shell which does not support brace expansion.

您仍然可以使用选项 -c 调用 bash 以便将 bash 与 system() 一起使用.例如:

You can still call bash with the option -c in order to use bash with system(). For example:

system("bash -c 'echo The shell is: $SHELL'")

bash 本身将在另一个 shell 之上运行(即:shell system() 调用)，但 echo 命令将肯定在 Bash 中运行.

bash itself will run on top of the other shell (i.e.: the shell system() invokes), but the echo command will definitely run in Bash.

通过在您的代码中应用相同的原则:

By applying the same principle in your code:

sprintf(command,"bash -c 'cat tmp/file{1..%d} > file.Ver'",num_of_points);

将创建您需要传递给 system() 的正确 command 字符串，以便命令 cat tmp/file{1..%d}>file.Ver 在 Bash 中运行并进行大括号扩展.

will create the proper command string you need to pass to system(), so that the command cat tmp/file{1..%d} > file.Ver is run in Bash and brace expansion is performed.

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