基于 UNIX 的环境中的 TCP/IP 用户，下表列出了某些最常见的错误原因码 (errno)。

完整的错误列表可以在文件 /usr/include/sys/errno.h 中找到 Errno。针对每一种操作系统给出了errno 号码。

Errno AIX HP-UX Solaris UnixWare Linux 说明
EINTR 4 4 4 4 4 系统调用中断。
EAGAIN 11 11 11 11 11 资源临时不可用。
EBUSY 16 16 16 16 16 资源正忙。
EMFILE 24 24 24 24 24 每个进程文件描述符表已满。
EPIPE 32 32 32 32 32 管道断开。
EADDRINUSE 67 226 125 125 98 已经在使用指定的地址。
ENETDOWN 69 228 127 127 100 网络已停止。
ENETUNREACH 70 229 128 128 101 没有到达网络的可用路由。
ENETRESET 71 230 129 129 102 重设时网络已卸下了连接。
ECONNRESET 73 232 131 131 104 伙伴已重设了连接。
ENOBUFS 74 233 132 132 105 系统中没有足够的缓冲区空间资源可用来完成调用。
ENOTCONN 76 235 134 134 107 未连接套接字。
ETIMEDOUT 78 238 145 145 110 连接超时。
ECONNREFUSED 79 239 146 146 111 连接已被拒绝。若您正在尝试与数据库相连，则检查是否已成功启动了服务器上的数据库管理程序和 TCP/IP 协议支持。 若使用 SOCKS 协议支持，则还要确保在 SOCKS 服务器上已成功启动了 TCP/IP 协议支持。
EHOSTDOWN 80 241 147 147 147 主机已停机。
EHOSTUNREACH 81 242 148 148 113 没有到达主机的可用路由。
Linux Socket Errno错误代码列表

124EMEDIUMTYPE Wrong medium type
123 ENOMEDIUM No medium found
122EDQUOT Disk quota exceeded
121 EREMOTEIO Remote I/O error
120EISNAM Is a named type file
119ENAVAIL No XENIX semaphores available
118ENOTNAM Not a XENIX named type file
117EUCLEAN Structure needs cleaning
116ESTALE Stale NFS file handle
115 EINPROGRESS +Operation nowin progress
114EALREADY Operation already in progress
113 EHOSTUNREACH No route tohost
112 EHOSTDOWN Host is down
111 ECONNREFUSED Connection refused
110 ETIMEDOUT +Connection timed out
109 ETOOMANYREFS Too manyreferences: cannot splice
108 ESHUTDOWN Cannot send after transport endpoint shutdown
107ENOTCONN Transport endpoint is not connected
106EISCONN Transport endpoint is alreadyconnected
105ENOBUFS No buffer space available
104 ECONNRESET Connection reset by peer
103 ECONNABORTED Softwarecaused connection abort
102 ENETRESET Network dropped connection on reset
101 ENETUNREACH Networkis unreachable
100ENETDOWN Network is down
99 EADDRNOTAVAIL Cannot assignrequested address
98 EADDRINUSE Address already in use
97 EAFNOSUPPORT Addressfamily not supported by protocol
96 EPFNOSUPPORT Protocolfamily not supported
95 EOPNOTSUPP Operation not supported
94 ESOCKTNOSUPPORT Socket typenot supported
93 EPROTONOSUPPORT Protocol notsupported
92 ENOPROTOOPT Protocol not available
91 EPROTOTYPE Protocol wrong type for socket
90EMSGSIZE +Message too long
89 EDESTADDRREQ Destination address required
88ENOTSOCK Socket operation on non-socket
87EUSERS Too many users
86ESTRPIPE Streams pipe error
85 ERESTART Interrupted system call should be restarted
84EILSEQ Invalid or incompletemultibyte or wide character
83ELIBEXEC Cannot exec a shared library directly
82ELIBMAX Attempting to link in too manyshared libraries
81 ELIBSCN .lib section in a.out corrupted
80ELIBBAD Accessing a corrupted shared library
79ELIBACC Can not access a needed sharedlibrary
78EREMCHG Remote address changed
77EBADFD File descriptor in bad state
76ENOTUNIQ Name not unique on network
75EOVERFLOW Value too large for defined data type
74EBADMSG +Bad message
73EDOTDOT RFS specific error
72EMULTIHOP Multihop attempted
71EPROTO Protocol error
70ECOMM Communication error onsend
69ESRMNT Srmount error
68EADV Advertise error
67ENOLINK Link has been severed
66EREMOTE Object is remote
65ENOPKG Package not installed
64ENONET Machine is not on the network
63ENOSR Out of streams resources
62ETIME Timer expired
61ENODATA No data available
60ENOSTR Device not a stream
59EBFONT Bad font file format
57EBADSLT Invalid slot
56EBADRQC Invalid request code
55ENOANO No anode
54EXFULL Exchange full
53EBADR Invalid request descriptor
52EBADE Invalid exchange
51EL2HLT Level 2 halted
50ENOCSI No CSI structure available
49EUNATCH Protocol driver not attached
48ELNRNG Link number out of range
47EL3RST Level 3 reset
46EL3HLT Level 3 halted
45EL2NSYNC Level 2 not synchronized
44ECHRNG Channel number out of range
43EIDRM Identifier removed
42ENOMSG No message of desired type
40ELOOP Too many levels ofsymbolic links
39 ENOTEMPTY +Directory not empty
38 ENOSYS +Function not implemented
37ENOLCK +No locks available
36 ENAMETOOLONG +File name toolong
35EDEADLK +Resource deadlock avoided
34ERANGE +Numerical result out of range
33EDOM +Numerical argument out ofdomain
32EPIPE +Broken pipe
31EMLINK +Too many links
30EROFS +Read-only file system
29ESPIPE +Illegal seek
28ENOSPC +No space left on device
27EFBIG +File too large
26ETXTBSY Text file busy
25ENOTTY +Inappropriate ioctl for device
24EMFILE +Too many open files
23ENFILE +Too many open files in system
22EINVAL +Invalid argument
21EISDIR +Is a directory
20ENOTDIR +Not a directory
19ENODEV +No such device
18EXDEV +Invalid cross-device link
17EEXIST +File exists
16EBUSY +Device or resource busy
15ENOTBLK Block device required
14 EFAULT +Bad address
13EACCES +Permission denied
12ENOMEM +Cannot allocate memory
11EAGAIN +Resource temporarily unavailable
10ECHILD +No child processes
9EBADF +Bad file descriptor
8ENOEXEC +Exec format error
7E2BIG +Argument list too long
6ENXIO +No such device or address
5EIO +Input/output error
4EINTR +Interrupted system call
3ESRCH +No such process
2ENOENT +No such file or directory
1EPERM +Operation not permitted
0-- Success