【python标准库】系统错误码errno

python

即标准的errno系统符号，与C语言中的errno.h相同，其数字代码所对应的文字描述可通过os.strerror来获取。

>>> for i in np.sort(list(errno.errorcode.keys())):
...   print(i,errno.errorcode[i],os.strerror(i))
...

其输出如下表

1	EPERM	Operation not permitted
2	ENOENT	No such file or directory
3	ESRCH	No such process
4	EINTR	Interrupted function call
5	EIO	Input/output error
6	ENXIO	No such device or address
7	E2BIG	Arg list too long
8	ENOEXEC	Exec format error
9	EBADF	Bad file descriptor
10	ECHILD	No child processes
11	EAGAIN	Resource temporarily unavailable
12	ENOMEM	Not enough space
13	EACCES	Permission denied
14	EFAULT	Bad address
16	EBUSY	Resource device
17	EEXIST	Fileexists
18	EXDEV	Improper link
19	ENODEV	No such device
20	ENOTDIR	Not a directory
21	EISDIR	Is a directory
22	EINVAL	Invalid argument
23	ENFILE	Too many open files in system
24	EMFILE	Too many open files
25	ENOTTY	Inappropriate I/O control operation
27	EFBIG	File too large
28	ENOSPC	No space left on device
29	ESPIPE	Invalid seek
30	EROFS	Read-only file system
31	EMLINK	Too many links
32	EPIPE	Broken pipe
33	EDOM	Domain error
34	ERANGE	Result too large
36	EDEADLOCK	Resource deadlock avoided
38	ENAMETOOLONG	Filename too long
39	ENOLCK	No locks available
40	ENOSYS	Function not implemented
41	ENOTEMPTY	Directory not empty
42	EILSEQ	Illegal byte sequence
104	EBADMSG	bad message
105	ECANCELED	operation canceled
111	EIDRM	identifier removed
120	ENODATA	no message available
121	ENOLINK	no link
122	ENOMSG	no message
124	ENOSR	no stream resources
125	ENOSTR	not a stream
127	ENOTRECOVERABLE	state not recoverable
129	ENOTSUP	not supported
132	EOVERFLOW	value too large
133	EOWNERDEAD	owner dead
134	EPROTO	protocol error
137	ETIME	stream timeout
139	ETXTBSY	text file busy

C语言

在C语言中，errno.h定义了整数变量errno，用于表明错误类型，程序启动时，errno为零。其实，Python中对错误码的解读也来自于此。

如果该值不为0，说明发生了错误，操作系统会定义各种错误码所对应的错误类型，例如2表示未找到文件或文件夹等，而错误号所对应的错误类型被封装在string.h中，可通过函数strerror()来搜索。

#include
#include
#include

int main(){
	for(int i=0; i<10; i++)
		printf("%d:%s\n",i,strerror(i));
	return 0;
}

编译运行

>gcc testErr.c
>a.exe
0:No error
1:Operation not permitted
2:No such file or directory
3:No such process
4:Interrupted function call
5:Input/output error
6:No such device or address
7:Arg list too long
8:Exec format error
9:Bad file descriptor

所以我们测试一下，若调用一个不存在的文件或文件夹，其main函数改为

int main(){
	FILE *fp;
	fp = fopen("test.txt","r");
	if (fp==NULL)
		printf("%d:%s",errno, strerror(errno));
	return 0;
}

>gcc errFile.c
>a.exe
2:No such file or directory