背景
errno.h是C 编程语言标准库中的头文件。它定义了使用符号errno （“错误号”的缩写）报告和检索错误情况的宏。经常需要用来在内核态用户态返回错误寻找，本文以供快速检索。
常用函数与用法
strerror 根据errno获取文件
比如：
FILE *file = fopen("non_file.txt", "r");if (file == NULL) {// 输出错误信息printf("Error opening file: %s\n", strerror(errno));return EXIT_FAILURE;}
实战输出：
函数返回
某个地方执行事务可以直接用 return -Exxx 这里的Exxx就是下面的 errorno的宏定义， 比如return -EPERM;表示没有权限
头文件
errno.h
对应关系
#define EPERM 1 /* Not super-user */
#define ENOENT 2 /* No such file or directory */
#define ESRCH 3 /* No such process */
#define EINTR 4 /* Interrupted system call */
#define EIO 5 /* I/O error */
#define ENXIO 6 /* No such device or address */
#define E2BIG 7 /* Arg list too long */
#define ENOEXEC 8 /* Exec format error */
#define EBADF 9 /* Bad file number */
#define ECHILD 10 /* No children */
#define EAGAIN 11 /* No more processes */
#define ENOMEM 12 /* Not enough core */
#define EACCES 13 /* Permission denied */
#define EFAULT 14 /* Bad address */
#define ENOTBLK 15 /* Block device required */
#define EBUSY 16 /* Mount device busy */
#define EEXIST 17 /* File exists */
#define EXDEV 18 /* Cross-device link */
#define ENODEV 19 /* No such device */
#define ENOTDIR 20 /* Not a directory */
#define EISDIR 21 /* Is a directory */
#define EINVAL 22 /* Invalid argument */
#define ENFILE 23 /* Too many open files in system */
#define EMFILE 24 /* Too many open files */
#define ENOTTY 25 /* Not a typewriter */
#define ETXTBSY 26 /* Text file busy */
#define EFBIG 27 /* File too large */
#define ENOSPC 28 /* No space left on device */
#define ESPIPE 29 /* Illegal seek */
#define EROFS 30 /* Read only file system */
#define EMLINK 31 /* Too many links */
#define EPIPE 32 /* Broken pipe */
#define EDOM 33 /* Math arg out of domain of func */
#define ERANGE 34 /* Math result not representable */
#define ENOMSG 35 /* No message of desired type */
#define EIDRM 36 /* Identifier removed */
#define ECHRNG 37 /* Channel number out of range */
#define EL2NSYNC 38 /* Level 2 not synchronized */
#define EL3HLT 39 /* Level 3 halted */
#define EL3RST 40 /* Level 3 reset */
#define ELNRNG 41 /* Link number out of range */
#define EUNATCH 42 /* Protocol driver not attached */
#define ENOCSI 43 /* No CSI structure available */
#define EL2HLT 44 /* Level 2 halted */
#define EDEADLK 45 /* Deadlock condition */
#define ENOLCK 46 /* No record locks available */
#define EBADE 50 /* Invalid exchange */
#define EBADR 51 /* Invalid request descriptor */
#define EXFULL 52 /* Exchange full */
#define ENOANO 53 /* No anode */
#define EBADRQC 54 /* Invalid request code */
#define EBADSLT 55 /* Invalid slot */
#define EDEADLOCK 56 /* File locking deadlock error */
#define EBFONT 57 /* Bad font file fmt */
#define ENOSTR 60 /* Device not a stream */
#define ENODATA 61 /* No data (for no delay io) */
#define ETIME 62 /* Timer expired */
#define ENOSR 63 /* Out of streams resources */
#define ENONET 64 /* Machine is not on the network */
#define ENOPKG 65 /* Package not installed */
#define EREMOTE 66 /* The object is remote */
#define ENOLINK 67 /* The link has been severed */
#define EADV 68 /* Advertise error */
#define ESRMNT 69 /* Srmount error */
#define ECOMM 70 /* Communication error on send */
#define EPROTO 71 /* Protocol error */
#define EMULTIHOP 74 /* Multihop attempted */
#define ELBIN 75 /* Inode is remote (not really error) */
#define EDOTDOT 76 /* Cross mount point (not really error) */
#define EBADMSG 77 /* Trying to read unreadable message */
#define EFTYPE 79 /* Inappropriate file type or format */
#define ENOTUNIQ 80 /* Given log. name not unique */
#define EBADFD 81 /* f.d. invalid for this operation */
#define EREMCHG 82 /* Remote address changed */
#define ELIBACC 83 /* Can't access a needed shared lib */
#define ELIBBAD 84 /* Accessing a corrupted shared lib */
#define ELIBSCN 85 /* .lib section in a.out corrupted */
#define ELIBMAX 86 /* Attempting to link in too many libs */
#define ELIBEXEC 87 /* Attempting to exec a shared library */
#define ENOSYS 88 /* Function not implemented */
#define ENMFILE 89 /* No more files */
#define ENOTEMPTY 90 /* Directory not empty */
#define ENAMETOOLONG 91 /* File or path name too long */
#define ELOOP 92 /* Too many symbolic links */
#define EOPNOTSUPP 95 /* Operation not supported on transport endpoint */
#define EPFNOSUPPORT 96 /* Protocol family not supported */
#define ECONNRESET 104 /* Connection reset by peer */
#define ENOBUFS 105 /* No buffer space available */
#define EAFNOSUPPORT 106 /* Address family not supported by protocol family */
#define EPROTOTYPE 107 /* Protocol wrong type for socket */
#define ENOTSOCK 108 /* Socket operation on non-socket */
#define ENOPROTOOPT 109 /* Protocol not available */
#define ESHUTDOWN 110 /* Can't send after socket shutdown */
#define ECONNREFUSED 111 /* Connection refused */
#define EADDRINUSE 112 /* Address already in use */
#define ECONNABORTED 113 /* Connection aborted */
#define ENETUNREACH 114 /* Network is unreachable */
#define ENETDOWN 115 /* Network interface is not configured */
#define ETIMEDOUT 116 /* Connection timed out */
#define EHOSTDOWN 117 /* Host is down */
#define EHOSTUNREACH 118 /* Host is unreachable */
#define EINPROGRESS 119 /* Connection already in progress */
#define EALREADY 120 /* Socket already connected */
#define EDESTADDRREQ 121 /* Destination address required */
#define EMSGSIZE 122 /* Message too long */
#define EPROTONOSUPPORT 123 /* Unknown protocol */
#define ESOCKTNOSUPPORT 124 /* Socket type not supported */
#define EADDRNOTAVAIL 125 /* Address not available */
#define ENETRESET 126
#define EISCONN 127 /* Socket is already connected */
#define ENOTCONN 128 /* Socket is not connected */
#define ETOOMANYREFS 129
#define EPROCLIM 130
#define EUSERS 131
#define EDQUOT 132
#define ESTALE 133
#define ENOTSUP 134 /* Not supported */
#define ENOMEDIUM 135 /* No medium (in tape drive) */
#define ENOSHARE 136 /* No such host or network path */
#define ECASECLASH 137 /* Filename exists with different case */
#define EILSEQ 138
#define EOVERFLOW 139 /* Value too large for defined data type */
POSIX中的errno
Symbol Value Description
EPERM 1 Operation not permitted
ENOENT 2 No such file or directory
ESRCH 3 No such process
EINTR 4 Interrupted system call
EIO 5 Input/output error
ENXIO 6 No such device or address
E2BIG 7 Argument list too long
ENOEXEC 8 Exec format error
EBADF 9 Bad file descriptor
ECHILD 10 No child processes
EAGAIN 11 Resource temporarily unavailable
ENOMEM 12 Cannot allocate memory
EACCES 13 Permission denied
EFAULT 14 Bad address
ENOTBLK 15 Block device required
EBUSY 16 Device or resource busy
EEXIST 17 File exists
EXDEV 18 Invalid cross-device link
ENODEV 19 No such device
ENOTDIR 20 Not a directory
EISDIR 21 Is a directory
EINVAL 22 Invalid argument
ENFILE 23 Too many open files in system
EMFILE 24 Too many open files
ENOTTY 25 Inappropriate ioctl for device
ETXTBSY 26 Text file busy
EFBIG 27 File too large
ENOSPC 28 No space left on device
ESPIPE 29 Illegal seek
EROFS 30 Read-only file system
EMLINK 31 Too many links
EPIPE 32 Broken pipe
EDOM 33 Numerical argument out of domain
ERANGE 34 Numerical result out of range
EDEADLK 35 Resource deadlock avoided
ENAMETOOLONG 36 File name too long
ENOLCK 37 No locks available
ENOSYS 38 Function not implemented
ENOTEMPTY 39 Directory not empty
ELOOP 40 Too many levels of symbolic links
ENOMSG 42 No message of desired type
EIDRM 43 Identifier removed
ECHRNG 44 Channel number out of range
EL2NSYNC 45 Level 2 not synchronized
EL3HLT 46 Level 3 halted
EL3RST 47 Level 3 reset
ELNRNG 48 Link number out of range
EUNATCH 49 Protocol driver not attached
ENOCSI 50 No CSI structure available
EL2HLT 51 Level 2 halted
EBADE 52 Invalid exchange
EBADR 53 Invalid request descriptor
EXFULL 54 Exchange full
ENOANO 55 No anode
EBADRQC 56 Invalid request code
EBADSLT 57 Invalid slot
EBFONT 59 Bad font file format
ENOSTR 60 Device not a stream
ENODATA 61 No data available
ETIME 62 Timer expired
ENOSR 63 Out of streams resources
ENONET 64 Machine is not on the network
ENOPKG 65 Package not installed
EREMOTE 66 Object is remote
ENOLINK 67 Link has been severed
EADV 68 Advertise error
ESRMNT 69 Srmount error
ECOMM 70 Communication error on send
EPROTO 71 Protocol error
EMULTIHOP 72 Multihop attempted
EDOTDOT 73 RFS specific error
EBADMSG 74 Bad message
EOVERFLOW 75 Value too large for defined data type
ENOTUNIQ 76 Name not unique on network
EBADFD 77 File descriptor in bad state
EREMCHG 78 Remote address changed
ELIBACC 79 Can not access a needed shared library
ELIBBAD 80 Accessing a corrupted shared library
ELIBSCN 81 .lib section in a.out corrupted
ELIBMAX 82 Attempting to link in too many shared libraries
ELIBEXEC 83 Cannot exec a shared library directly
EILSEQ 84 Invalid or incomplete multibyte or wide character
ERESTART 85 Interrupted system call should be restarted
ESTRPIPE 86 Streams pipe error
EUSERS 87 Too many users
ENOTSOCK 88 Socket operation on non-socket
EDESTADDRREQ 89 Destination address required
EMSGSIZE 90 Message too long
EPROTOTYPE 91 Protocol wrong type for socket
ENOPROTOOPT 92 Protocol not available
EPROTONOSUPPORT 93 Protocol not supported
ESOCKTNOSUPPORT 94 Socket type not supported
EOPNOTSUPP 95 Operation not supported
EPFNOSUPPORT 96 Protocol family not supported
EAFNOSUPPORT 97 Address family not supported by protocol
EADDRINUSE 98 Address already in use
EADDRNOTAVAIL 99 Cannot assign requested address
ENETDOWN 100 Network is down
ENETUNREACH 101 Network is unreachable
ENETRESET 102 Network dropped connection on reset
ECONNABORTED 103 Software caused connection abort
ECONNRESET 104 Connection reset by peer
ENOBUFS 105 No buffer space available
EISCONN 106 Transport endpoint is already connected
ENOTCONN 107 Transport endpoint is not connected
ESHUTDOWN 108 Cannot send after transport endpoint shutdown
ETOOMANYREFS 109 Too many references: cannot splice
ETIMEDOUT 110 Connection timed out
ECONNREFUSED 111 Connection refused
EHOSTDOWN 112 Host is down
EHOSTUNREACH 113 No route to host
EALREADY 114 Operation already in progress
EINPROGRESS 115 Operation now in progress
ESTALE 116 Stale file handle
EUCLEAN 117 Structure needs cleaning
ENOTNAM 118 Not a XENIX named type file
ENAVAIL 119 No XENIX semaphores available
EISNAM 120 Is a named type file
EREMOTEIO 121 Remote I/O error
EDQUOT 122 Disk quota exceeded
ENOMEDIUM 123 No medium found
EMEDIUMTYPE 124 Wrong medium type
ECANCELED 125 Operation canceled
ENOKEY 126 Required key not available
EKEYEXPIRED 127 Key has expired
EKEYREVOKED 128 Key has been revoked
EKEYREJECTED 129 Key was rejected by service
EOWNERDEAD 130 Owner died
ENOTRECOVERABLE 131 State not recoverable
ERFKILL 132 Operation not possible due to RF-kill
EHWPOISON 133 Memory page has hardware error
其他获取方式
man手册获取 man errno
还可以通过man手册动态获取，命令：man errno
使用errno命令获取 errno -l
如果没有需要安装比如ubuntu是 moreutils安装包：apt install moreutils
- 安装moreutils包安装errno命令
- errno -l 查看输出
参考：
https://en.wikipedia.org/wiki/Errno.h