Linux系统上的文件打印UID [英] printing uid of a file on linux system

问题描述

我正在学习C语言编程。我努力使自己的程序类似的 LS 命令，但用量少options.what我做的是采取输入目录/文件名作为参数，然后用得到的的dirent 结构（如果是目录）。

i am learning c programming. I am trying to make my own program similar to ls command but with less options.what i am doing is taking input directory/file name as argument and then gets all directory entry with dirent struct(if it is directory) .

在这我使用stat（）取文件的所有信息，但这里是我的问题，当我使用write（）来打印这些看重其优良的，但是当我想用printf的打印这些（）我得到warninng：格式'％ld个'需要键入长整型，但参数2的类型__uid_t。我不知道什么应该在的地方使用％LD ，也为其他特殊的数据类型。

After it i use stat() to take all information of the file but here is my problem when i use write() to print these value its fine but when i want to print these with printf() i get warninng : format ‘%ld’ expects type ‘long int’, but argument 2 has type ‘__uid_t’. I don't know what should use at place of %ld and also for other special data types.

推荐答案

有是 __将uid_t 无格式说明，因为这种类型是系统特定的，不是部分的C标准，因此的printf 是没有意识到这一点。

There is no format specifier for __uid_t, because this type is system-specific and is not the part of C standard, and hence printf is not aware of it.

通常的解决方法是将其提升到能够适合所有的你的目标系统UID值的整个范围内的类型：

The usual workaround is to promote it to a type that would fit the entire range of UID values on all the systems you are targeting:

printf("%lu\n", (unsigned long int)uid); /* some systems support 32-bit UIDs */

这篇关于Linux系统上的文件打印UID的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！