errno 错误表
errno 是记录系统的最后一次错误代码。代码是一个int型的值，在errno.h中定义
注意：只有当一个库函数失败时，errno才会被设置。当函数成功运行时，errno的值不会被修改。这意味着我们不能通过测试errno的值来判断是否有错误存在。反之，只有当被调用的函数提示有错误发生时检查errno的值才有意义。
错误表
| 错误数 | 描述 |
|---|---|
| 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 processe |
| 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 |
