Linux中系統呼叫的錯誤都儲存於errno中，errno由作業系統維護，儲存就近發生的錯誤，即下一次的錯誤碼會覆蓋掉上一次的錯誤。

錯誤碼描述如下 0 表示成功

errno: 0 Success

errno: 1 Operation not permitted

errno: 2 No such file or directory

errno: 3 No such process

errno: 4 Interrupted system call

errno: 5 Input/output error

errno: 6 No such device or address

errno: 7 Argument list too long

errno: 8 Exec format error

errno: 9 Bad file descriptor

errno: 10 No child processes

errno: 11 Resource temporarily unavailable

errno: 12 Cannot allocate memory

errno: 13 Permission denied

errno: 14 Bad address

errno: 15 Block device required

errno: 16 Device or resource busy

errno: 17 File exists

errno: 18 Invalid cross-device link

errno: 19 No such device

errno: 20 Not a directory

errno: 21 Is a directory

errno: 22 Invalid argument

errno: 23 Too many open files in system

errno: 24 Too many open files

errno: 25 Inappropriate ioctl for device

errno: 26 Text file busy

errno: 27 File too large

errno: 28 No space left on device

errno: 29 Illegal seek

errno: 30 Read-only file system

errno: 31 Too many links

errno: 32 Broken pipe

errno: 33 Numerical argument out of domain

errno: 34 Numerical result out of range

errno: 35 Resource deadlock avoided

errno: 36 File name too long

errno: 37 No locks available

errno: 38 Function not implemented

errno: 39 Directory not empty

errno: 40 Too many levels of symbolic links

errno: 41 Unknown error 41

errno: 42 No message of desired type

errno: 43 Identifier removed

errno: 44 Channel number out of range

errno: 45 Level 2 not synchronized

errno: 46 Level 3 halted

errno: 47 Level 3 reset

errno: 48 Link number out of range

errno: 49 Protocol driver not attached

errno: 50 No CSI structure available

errno: 51 Level 2 halted

errno: 52 Invalid exchange

errno: 53 Invalid request descriptor

errno: 54 Exchange full

errno: 55 No anode

errno: 56 Invalid request code

errno: 57 Invalid slot

errno: 58 Unknown error 58

errno: 59 Bad font file format

errno: 60 Device not a stream

errno: 61 No data available

errno: 62 Timer expired

errno: 63 Out of streams resources

errno: 64 Machine is not on the network

errno: 65 Package not installed

errno: 66 Object is remote

errno: 67 Link has been severed

errno: 68 Advertise error

errno: 69 Srmount error

errno: 70 Communication error on send

errno: 71 Protocol error

errno: 72 Multihop attempted

errno: 73 RFS specific error

errno: 74 Bad message

errno: 75 Value too large for defined data type

errno: 76 Name not unique on network

errno: 77 File descriptor in bad state

errno: 78 Remote address changed

errno: 79 Can not access a needed shared library

errno: 80 Accessing a corrupted shared library

errno: 81 .lib section in a.out corrupted

errno: 82 Attempting to link in too many shared libraries

errno: 83 Cannot exec a shared library directly

errno: 84 Invalid or incomplete multibyte or wide character

errno: 85 Interrupted system call should be restarted

errno: 86 Streams pipe error

errno: 87 Too many users

errno: 88 Socket operation on non-socket

errno: 89 Destination address required

errno: 90 Message too long

errno: 91 Protocol wrong type for socket

errno: 92 Protocol not available

errno: 93 Protocol not supported

errno: 94 Socket type not supported

errno: 95 Operation not supported

errno: 96 Protocol family not supported

errno: 97 Address family not supported by protocol

errno: 98 Address already in use

errno: 99 Cannot assign requested address

errno: 100 Network is down

errno: 101 Network is unreachable

errno: 102 Network dropped connection on reset

errno: 103 Software caused connection abort

errno: 104 Connection reset by peer

errno: 105 No buffer space available

errno: 106 Transport endpoint is already connected

errno: 107 Transport endpoint is not connected

errno: 108 Cannot send after transport endpoint shutdown

errno: 109 Too many references: cannot splice

errno: 110 Connection timed out

errno: 111 Connection refused

errno: 112 Host is down

errno: 113 No route to host

errno: 114 Operation already in progress

errno: 115 Operation now in progress

errno: 116 Stale file handle

errno: 117 Structure needs cleaning

errno: 118 Not a XENIX named type file

errno: 119 No XENIX semaphores available

errno: 120 Is a named type file

errno: 121 Remote I/O error

errno: 122 Disk quota exceeded

errno: 123 No medium found

errno: 124 Wrong medium type

errno: 125 Operation canceled

errno: 126 Required key not available

errno: 127 Key has expired

errno: 128 Key has been revoked

errno: 129 Key was rejected by service

errno: 130 Owner died

errno: 131 State not recoverable

errno: 132 Operation not possible due to RF-kill

errno: 133 Memory page has hardware error

errno: 134~255 unknown error!

Linux中，在標頭檔案/usr/include/asm-generic/errno-base.h對基礎常用errno進行了巨集定義：

#ifndef _ASM_GENERIC_ERRNO_BASE_H
#define _ASM_GENERIC_ERRNO_BASE_H

#define EPERM        1  /* Operation not permitted */
#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  /* Argument list too long */
#define ENOEXEC      8  /* Exec format error */
#define EBADF        9  /* Bad file number */
#define ECHILD      10  /* No child processes */
#define EAGAIN      11  /* Try again */
#define ENOMEM      12  /* Out of memory */
#define EACCES      13  /* Permission denied */
#define EFAULT      14  /* Bad address */
#define ENOTBLK     15  /* Block device required */
#define EBUSY       16  /* Device or resource 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  /* File table overflow */
#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 argument out of domain of func */
#define ERANGE      34  /* Math result not representable */

#endif

在/usr/include/asm-asm-generic/errno.h中，對剩餘的errno做了巨集定義：

#ifndef _ASM_GENERIC_ERRNO_H
#define _ASM_GENERIC_ERRNO_H

#include <asm-generic/errno-base.h>

#define EDEADLK     35  /* Resource deadlock would occur */
#define ENAMETOOLONG    36  /* File name too long */
#define ENOLCK      37  /* No record locks available */
#define ENOSYS      38  /* Function not implemented */
#define ENOTEMPTY   39  /* Directory not empty */
#define ELOOP       40  /* Too many symbolic links encountered */
#define EWOULDBLOCK EAGAIN  /* Operation would block */
#define ENOMSG      42  /* No message of desired type */
#define EIDRM       43  /* Identifier removed */
#define ECHRNG      44  /* Channel number out of range */
#define EL2NSYNC    45  /* Level 2 not synchronized */
#define EL3HLT      46  /* Level 3 halted */
#define EL3RST      47  /* Level 3 reset */
#define ELNRNG      48  /* Link number out of range */
#define EUNATCH     49  /* Protocol driver not attached */
#define ENOCSI      50  /* No CSI structure available */
#define EL2HLT      51  /* Level 2 halted */
#define EBADE       52  /* Invalid exchange */
#define EBADR       53  /* Invalid request descriptor */
#define EXFULL      54  /* Exchange full */
#define ENOANO      55  /* No anode */
#define EBADRQC     56  /* Invalid request code */
#define EBADSLT     57  /* Invalid slot */

#define EDEADLOCK   EDEADLK

#define EBFONT      59  /* Bad font file format */
#define ENOSTR      60  /* Device not a stream */
#define ENODATA     61  /* No data available */
#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  /* Object is remote */
#define ENOLINK     67  /* 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   72  /* Multihop attempted */
#define EDOTDOT     73  /* RFS specific error */
#define EBADMSG     74  /* Not a data message */
#define EOVERFLOW   75  /* Value too large for defined data type */
#define ENOTUNIQ    76  /* Name not unique on network */
#define EBADFD      77  /* File descriptor in bad state */
#define EREMCHG     78  /* Remote address changed */
#define ELIBACC     79  /* Can not access a needed shared library */
#define ELIBBAD     80  /* Accessing a corrupted shared library */
#define ELIBSCN     81  /* .lib section in a.out corrupted */
#define ELIBMAX     82  /* Attempting to link in too many shared libraries */

#define ELIBEXEC    83  /* Cannot exec a shared library directly */
#define EILSEQ      84  /* Illegal byte sequence */
#define ERESTART    85  /* Interrupted system call should be restarted */
#define ESTRPIPE    86  /* Streams pipe error */
#define EUSERS      87  /* Too many users */
#define ENOTSOCK    88  /* Socket operation on non-socket */
#define EDESTADDRREQ    89  /* Destination address required */
#define EMSGSIZE    90  /* Message too long */
#define EPROTOTYPE  91  /* Protocol wrong type for socket */
#define ENOPROTOOPT 92  /* Protocol not available */
#define EPROTONOSUPPORT 93  /* Protocol not supported */
#define ESOCKTNOSUPPORT 94  /* Socket type not supported */
#define EOPNOTSUPP  95  /* Operation not supported on transport endpoint */
#define EPFNOSUPPORT    96  /* Protocol family not supported */
#define EAFNOSUPPORT    97  /* Address family not supported by protocol */
#define EADDRINUSE  98  /* Address already in use */
#define EADDRNOTAVAIL   99  /* Cannot assign requested address */
#define ENETDOWN    100 /* Network is down */
#define ENETUNREACH 101 /* Network is unreachable */
#define ENETRESET   102 /* Network dropped connection because of reset */
#define ECONNABORTED    103 /* Software caused connection abort */
#define ECONNRESET  104 /* Connection reset by peer */
#define ENOBUFS     105 /* No buffer space available */
#define EISCONN     106 /* Transport endpoint is already connected */
#define ENOTCONN    107 /* Transport endpoint is not connected */
#define ESHUTDOWN   108 /* Cannot send after transport endpoint shutdown */
#define ETOOMANYREFS    109 /* Too many references: cannot splice */
#define ETIMEDOUT   110 /* Connection timed out */
#define ECONNREFUSED    111 /* Connection refused */
#define EHOSTDOWN   112 /* Host is down */
#define EHOSTUNREACH    113 /* No route to host */
#define EALREADY    114 /* Operation already in progress */
#define EINPROGRESS 115 /* Operation now in progress */
#define ESTALE      116 /* Stale file handle */
#define EUCLEAN     117 /* Structure needs cleaning */
#define ENOTNAM     118 /* Not a XENIX named type file */
#define ENAVAIL     119 /* No XENIX semaphores available */
#define EISNAM      120 /* Is a named type file */
#define EREMOTEIO   121 /* Remote I/O error */
#define EDQUOT      122 /* Quota exceeded */

#define ENOMEDIUM   123 /* No medium found */
#define EMEDIUMTYPE 124 /* Wrong medium type */
#define ECANCELED   125 /* Operation Canceled */
#define ENOKEY      126 /* Required key not available */
#define EKEYEXPIRED 127 /* Key has expired */
#define EKEYREVOKED 128 /* Key has been revoked */
#define EKEYREJECTED    129 /* Key was rejected by service */

/* for robust mutexes */
#define EOWNERDEAD  130 /* Owner died */
#define ENOTRECOVERABLE 131 /* State not recoverable */

#define ERFKILL     132 /* Operation not possible due to RF-kill */

#define EHWPOISON   133 /* Memory page has hardware error */

#endif