errno 在 <errno.h> 中定義，錯誤 Exx 的宏定義在 /usr/include/asm-generic 文件夾下面的 errno-base.h 和 errno.h，分別定義了 1-34 、35-132 的錯誤定義。
strerror() 函數依據 errno 值返回錯誤描述字符串，下面程序打印對照表：
01.#include <errno.h>
02.#include <string.h>
03.#include <stdio.h>
04.
05.int main()
06.
{
07. int i;
08. for(i = 0; i < 140; ++i)
09. {
10. errno = i;
11. printf("errno %d :\t\t%s\n",i,strerror(errno));
12. }
13. return 0;
14.}
錯誤對照表：
errno0 : Success
errno1 : Operation not permitted
errno2 : No such file or directory
errno3 : No such process
errno4 : Interrupted system call
errno5 : Input/output error
errno6 : No such device or address
errno7 : Argument list too long
errno8 : Exec format error
errno9 : Bad file descriptor
errno10 : No child processes
errno11 : Resource temporarily unavailable
errno12 : Cannot allocate memory
errno13 : Permission denied
errno14 : Bad address
errno15 : Block device required
errno16 : Device or resource busy
errno17 : File exists
errno18 : Invalid cross-device link
errno19 : No such device
errno20 : Not a directory
errno21 : Is a directory
errno22 : Invalid argument
errno23 : Too many open files in system
errno24 : Too many open files
errno25 : Inappropriate ioctl for device
errno26 : Text file busy
errno27 : File too large
errno28 : No space left on device
errno29 : Illegal seek
errno30 : Read-only file system
errno31 : Too many links
errno32 : Broken pipe
errno33 : Numerical argument out of domain
errno34 : Numerical result out of range
errno35 : Resource deadlock avoided
errno36 : File name too long
errno37 : No locks available
errno38 : Function not implemented
errno39 : Directory not empty
errno40 : Too many levels of symbolic links
errno41 : Unknown error 41
errno42 : No message of desired type
errno43 : Identifier removed
errno44 : Channel number out of range
errno45 : Level 2 not synchronized
errno46 : Level 3 halted
errno47 : Level 3 reset
errno48 : Link number out of range
errno49 : Protocol driver not attached
errno50 : No CSI structure available
errno51 : Level 2 halted
errno52 : Invalid exchange
errno53 : Invalid request descriptor
errno54 : Exchange full
errno55 : No anode
errno56 : Invalid request code
errno57 : Invalid slot
errno58 : Unknown error 58
errno59 : Bad font file format
errno60 : Device not a stream
errno61 : No data available
errno62 : Timer expired
errno63 : Out of streams resources
errno64 : Machine is not on the network
errno65 : Package not installed
errno66 : Object is remote
errno67 : Link has been severed
errno68 : Advertise error
errno69 : Srmount error
errno70 : Communication error on send
errno71 : Protocol error
errno72 : Multihop attempted
errno73 : RFS specific error
errno74 : Bad message
errno75 : Value too large for defined datatype
errno76 : Name not unique on network
errno77 : File descriptor in bad state
errno78 : Remote address changed
errno79 : Can not access a needed sharedlibrary
errno80 : Accessing a corrupted sharedlibrary
errno81 : .lib section in a.out corrupted
errno82 : Attempting to link in too manyshared libraries
errno83 : Cannot exec a shared librarydirectly
errno84 : Invalid or incomplete multibyte orwide character
errno85 : Interrupted system call should berestarted
errno86 : Streams pipe error
errno87 : Too many users
errno88 : Socket operation on non-socket
errno89 : Destinationaddress required
errno90 : Message too long
errno91 : Protocol wrong type for socket
errno92 : Protocol not available
errno93 : Protocol not supported
errno94 : Socket type not supported
errno95 : Operation not supported
errno96 : Protocol family not supported
errno97 : Address family not supported byprotocol
errno98 : Address already in use
errno99 : Cannot assign requested address
errno100 : Network is down
errno101 : Network is unreachable
errno102 : Network dropped connection onreset
errno103 : Software caused connection abort
errno104 : Connection reset by peer
errno105 : No buffer space available
errno106 : Transport endpoint is alreadyconnected
errno107 : Transport endpoint is notconnected
errno108 : Cannot send after transportendpoint shutdown
errno109 : Too many references: cannot splice
errno110 : Connection timed out
errno111 : Connection refused
errno112 : Host is down
errno113 : No route to host
errno114 : Operation already in progress
errno115 : Operation now in progress
errno116 : Stale NFS file handle
errno117 : Structure needs cleaning
errno118 : Not a XENIX named type file
errno119 : No XENIX semaphores available
errno120 : Is a named type file
errno121 : Remote I/O error
errno122 : Disk quota exceeded
errno123 : No medium found
errno124 : Wrong medium type
errno125 : Operation canceled
errno126 : Required key not available
errno127 : Key has expired
errno128 : Key has been revoked
errno129 : Key was rejected by service
errno130 : Owner died
errno131 : State not recoverable
errno132 : Operation not possible due toRF-kill
errno133 : Unknown error 133
errno134 : Unknown error 134
errno135 : Unknown error 135
errno136 : Unknown error 136
errno137 : Unknown error 137
errno138 : Unknown error 138
errno139 : Unknown error 139
由上可見Linux對錯誤宏的定義。
頭文件 /usr/include/asm-generic/errno-base.h 的源碼：
#ifndef _ASM_GENERIC_ERRNO_BASE_H
#define _ASM_GENERIC_ERRNO_BASE_H
#define EPERM 1 /* Operation not permitted */
#define ENOENT2 /* 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 /* Argument list too long */
#define ENOEXEC8 /* Exec format error */
#define EBADF 9 /* Bad file number */
#define ECHILD10 /* No child processes */
#define EAGAIN11 /* Try again */
#define ENOMEM12 /* Out of memory */
#define EACCES13 /* Permission denied */
#define EFAULT14 /* Bad address */
#define ENOTBLK15 /* Block device required */
#define EBUSY 16 /* Device or resource busy */
#define EEXIST17 /* File exists */
#define EXDEV 18 /* Cross-device link */
#define ENODEV19 /* No such device */
#define ENOTDIR20 /* Not a directory */
#define EISDIR21 /* Is a directory */
#define EINVAL22 /* Invalid argument */
#define ENFILE23 /* File table overflow */
#define EMFILE24 /* Too many open files */
#define ENOTTY25 /* Not a typewriter */
#define ETXTBSY26 /* Text file busy */
#define EFBIG 27 /* File too large */
#define ENOSPC28 /* No space left on device */
#define ESPIPE29 /* Illegal seek */
#define EROFS 30 /* Read-only file system */
#define EMLINK31 /* Too many links */
#define EPIPE 32 /* Broken pipe */
#define EDOM 33 /* Math argument out of domain of func */
#define ERANGE34 /* Math result not representable */
#endif
頭文件/usr/include/asm-generic/erno.h源碼：
#ifndef _ASM_GENERIC_ERRNO_H
#define _ASM_GENERIC_ERRNO_H
#include <asm-generic/errno-base.h>
#define EDEADLK35 /* Resource deadlock would occur */
#define ENAMETOOLONG36 /* File name too long */
#define ENOLCK37 /* No record locks available */
#define ENOSYS38 /* Function not implemented */
#define ENOTEMPTY39 /* Directory not empty */
#define ELOOP 40 /* Too many symbolic links encountered */
#define EWOULDBLOCKEAGAIN /* Operation would block */
#define ENOMSG42 /* No message of desired type */
#define EIDRM 43 /* Identifier removed */
#define ECHRNG44 /* Channel number out of range */
#define EL2NSYNC45 /* Level 2 not synchronized */
#define EL3HLT46 /* Level 3 halted */
#define EL3RST47 /* Level 3 reset */
#define ELNRNG48 /* Link number out of range */
#define EUNATCH49 /* Protocol driver not attached */
#define ENOCSI50 /* No CSI structure available */
#define EL2HLT51 /* Level 2 halted */
#define EBADE 52 /* Invalid exchange */
#define EBADR 53 /* Invalid request descriptor */
#define EXFULL54 /* Exchange full */
#define ENOANO55 /* No anode */
#define EBADRQC56 /* Invalid request code */
#define EBADSLT57 /* Invalid slot */
#define EDEADLOCKEDEADLK
#define EBFONT59 /* Bad font file format */
#define ENOSTR60 /* Device not a stream */
#define ENODATA61 /* No data available */
#define ETIME 62 /* Timer expired */
#define ENOSR 63 /* Out of streams resources */
#define ENONET64 /* Machine is not on the network */
#define ENOPKG65 /* Package not installed */
#define EREMOTE66 /* Object is remote */
#define ENOLINK67 /* Link has been severed */
#define EADV 68 /* Advertise error */
#define ESRMNT69 /* Srmount error */
#define ECOMM 70 /* Communication error on send */
#define EPROTO71 /* Protocol error */
#define EMULTIHOP72 /* Multihop attempted */
#define EDOTDOT73 /* RFS specific error */
#define EBADMSG74 /* Not a data message */
#define EOVERFLOW75 /* Value too large for defined data type */
#define ENOTUNIQ76 /* Name not unique on network */
#define EBADFD77 /* File descriptor in bad state */
#define EREMCHG78 /* Remote address changed */
#define ELIBACC79 /* Can not access a needed shared library */
#define ELIBBAD80 /* Accessing a corrupted shared library */
#define ELIBSCN81 /* .lib section in a.out corrupted */
#define ELIBMAX82 /* Attempting to link in too many shared libraries */
#define ELIBEXEC83 /* Cannot exec a shared library directly */
#define EILSEQ84 /* Illegal byte sequence */
#define ERESTART85 /* Interrupted system call should be restarted */
#define ESTRPIPE86 /* Streams pipe error */
#define EUSERS87 /* Too many users */
#define ENOTSOCK88 /* Socket operation on non-socket */
#define EDESTADDRREQ89 /* Destination address required */
#define EMSGSIZE90 /* Message too long */
#define EPROTOTYPE91 /* Protocol wrong type for socket */
#define ENOPROTOOPT92 /* Protocol not available */
#define EPROTONOSUPPORT93 /* Protocol not supported */
#define ESOCKTNOSUPPORT94 /* Socket type not supported */
#define EOPNOTSUPP95 /* Operation not supported on transport endpoint */
#define EPFNOSUPPORT96 /* Protocol family not supported */
#define EAFNOSUPPORT97 /* Address family not supported by protocol */
#define EADDRINUSE98 /* Address already in use */
#define EADDRNOTAVAIL99 /* Cannot assign requested address */
#define ENETDOWN100 /* Network is down */
#define ENETUNREACH101 /* Network is unreachable */
#define ENETRESET102 /* Network dropped connection because of reset */
#define ECONNABORTED103 /* Software caused connection abort */
#define ECONNRESET104 /* Connection reset by peer */
#define ENOBUFS105 /* No buffer space available */
#define EISCONN106 /* Transport endpoint is already connected */
#define ENOTCONN107 /* Transport endpoint is not connected */
#define ESHUTDOWN108 /* Cannot send after transport endpoint shutdown */
#define ETOOMANYREFS109 /* Too many references: cannot splice */
#define ETIMEDOUT110 /* Connection timed out */
#define ECONNREFUSED111 /* Connection refused */
#define EHOSTDOWN112 /* Host is down */
#define EHOSTUNREACH113 /* No route to host */
#define EALREADY114 /* Operation already in progress */
#define EINPROGRESS115 /* Operation now in progress */
#define ESTALE116 /* Stale NFS file handle */
#define EUCLEAN117 /* Structure needs cleaning */
#define ENOTNAM118 /* Not a XENIX named type file */
#define ENAVAIL119 /* No XENIX semaphores available */
#define EISNAM120 /* Is a named type file */
#define EREMOTEIO121 /* Remote I/O error */
#define EDQUOT122 /* Quota exceeded */
#define ENOMEDIUM123 /* No medium found */
#define EMEDIUMTYPE124 /* Wrong medium type */
#define ECANCELED125 /* Operation Canceled */
#define ENOKEY126 /* Required key not available */
#define EKEYEXPIRED127 /* Key has expired */
#define EKEYREVOKED128 /* Key has been revoked */
#define EKEYREJECTED129 /* Key was rejected by service */
/* for robust mutexes */
#define EOWNERDEAD130 /* Owner died */
#define ENOTRECOVERABLE131 /* State not recoverable */
#define ERFKILL 132/* Operation not possible due to RF-kill */
#endif