我试图创建名为1 2 3 4的文件夹，使用下面的C ++程序。我可以在 RHEL 中成功实现。 但是，在 ubuntu 13.10 中创建了一个名为{1..4}的文件夹。
I was trying to create folders named 1 2 3 4, using the C++ program below. I can successfully achieve that in RHEL. However it created a folder named {1..4} in ubuntu 13.10.
为什么会发生这种情况？谢谢您帮助我！
Why does this happen? Thank you for helping me!
#include <cstdlib> int main() { std::system("mkdir {1..4}"); }这是我们产品中CPP单元测试的一部分。是的，它的丑陋。但我恐怕在这种情况下可以做的事很少。
It's a part of CPP unit test in our product. Yes, it's ugly. But I am afraid very few thing can be done in this situation.
你是对的。 在RHEL中， sh -c'echo {1..4}' 1 2 3 4
You are right. In RHEL, sh -c 'echo {1..4}' 1 2 3 4
在Ubuntu sh -c'echo {1..4}' {1..4}
In Ubuntu sh -c 'echo {1..4}' {1..4}
所以我使用下面的程序。有用！ #include
So I use the program below instead. It works! #include
int main() { std::system("bash -c 'mkdir {1..4}'"); }似乎系统默认使用sh ....谢谢你的回答！
seems system use sh by default....Thank you for your answer!
推荐答案有一点术语：Linux有文件系统中的％28个计算％29rel =nofollow>目录，不是文件夹（文件夹可以在桌面上可视化显示，但这是桌面细节）。
A bit of terminology: Linux has directories in its file systems, not "folders" (folders may appear visually on the desktop, but that is a desktop detail).
您不需要使用 system（3）（正在运行 sh 不 bash ！）。 和POSIX sh 不知道 {1..4} 符号，因此 {1..4} 字符串传递到 / bin / mkdir 命令a href =man7/linux/man-pages/man1/mkdir.1.html =nofollow> mkdir（1） ...）。
You don't need to use system(3) (which is running sh not bash!). And POSIX sh don't know the {1..4} notation, hence the {1..4} string is passed verbatim to /bin/mkdir command (see mkdir(1) ...).
执行
sh -c 'echo {1..4}'来测试 sh c $ c> {1..4} 符号。
to test that sh don't understand the {1..4} notation.
（所以这是一个在旧RHEL中的错误， $ c> / bin / sh 是 / bin / bash 的符号链接，而在Debian和Ubuntu上，它是符合Posix标准的符号链接，更快 / bin / dash ）
(so it is a bug in your old RHEL, where perhaps /bin/sh is a symlink to /bin/bash while on Debian and Ubuntu it is a symlink to the more Posix compliant and faster /bin/dash)
只需使用 mkdir（2）系统调用和代码
Just use the mkdir(2) syscall and code
#include <cstdlib> #include <cstdio> #include <sys/stat.h> #include <sys/types.h> int main() { for (int i=1; i<=4; i++) { char buf[8]; snprintf(buf, sizeof(buf), "%d", i); if (mkdir(buf, 0755)) { perror("mkdir"); exit(EXIT_FAILURE); }; } }我希望你不想创建单个目录 1 2 3 4 。这是可能和容易，但它真的是味道差。为了您的心理安全，在目录名称中只能使用字母，数字和下划线 _ 。
I hope you don't want to create a single directory named 1 2 3 4. It is possible and easy, but it really is poor taste. For your mental safety, use only letters, digits and underscores _ in directory names.
href =man7/linux/man-pages/man3/snprintf.3.html =nofollow> snprintf（3）将int转换为字符缓冲区。使用 C ++ 11 ，您可以使用 std :: to_string 和 c_str ...
I am using snprintf(3) to convert an int to a character buffer. With C++11 you could use std::to_string and c_str ...
阅读高级Linux编程 ...
使用 mkdir（2） syscall而不是通过 system（3）调用的命令有几个重要的优点：
Using the mkdir(2) syscall instead of going thru a command invoked by system(3) has several important advantages:
- 更快，您不需要 fork（2）一个 / bin / sh -c shell如 system（3）应该这样做。
- 它使用更少的资源，因为没有额外的进程是 fork ，因此您的程序将仍然运行，当你达到你的极限（见 setrlimit（2） ...）
- 它更可靠。应该 mkdir（2）失败，你可以（而且应该）很好地处理故障。请参见 errno（3）和 strerror（3） ....
- it is much faster, you don't need to fork(2) a /bin/sh -c shell like system(3) should do.
- it uses much less resources, since no additional process is fork-ed, so your program will still run when you have reached your limits (see setrlimit(2) ...)
- it is more reliable. Should mkdir(2) fail you could (and should) handle the failure nicely. See errno(3) and strerror(3) ....
更多推荐
为什么mkdir的行为在不同的Linux发行版上有所不同？
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