1. 错误码 / errno

Linux中系统调用的错误都存储于 errno中，errno由操作系统维护，存储就近发生的错误，即下一次的错误码会覆盖掉上一次的错误。

PS: 只有当系统调用或者调用lib函数时出错，才会置位errno！

查看系统中所有的errno所代表的含义，可以采用如下的代码：

/* Function: obtain the errno string * char *strerror(int errno) */ #include  #include  //for strerror() //#include  int main() { int tmp = 0; for(tmp = 0; tmp <=256; tmp++) { printf("errno: %2d\t%s\n",tmp,strerror(tmp)); } return 0; }

输出信息如下：

errno: 0 Success errno: 1 Operation not permitted errno: 2 No such file or directory errno: 3 No such process errno: 4 Interrupted system callerrno: 5 Input/output errorerrno: 6 No such device or address errno: 7 Argument list too longerrno: 8 Exec format errorerrno: 9 Bad file descriptorerrno: 10 No child processes errno: 11 Resource temporarily unavailable errno: 12 Cannot allocate memoryerrno: 13 Permission denied errno: 14 Bad address errno: 15 Block device requirederrno: 16 Device or resource busy errno: 17 File existserrno: 18 Invalid cross-device linkerrno: 19 No such device errno: 20 Not a directoryerrno: 21 Is a directoryerrno: 22 Invalid argument errno: 23 Too many open files in systemerrno: 24 Too many open files errno: 25 Inappropriate ioctl for device errno: 26 Text file busy errno: 27 File too largeerrno: 28 No space left on device errno: 29 Illegal seek errno: 30 Read-only file systemerrno: 31 Too many links errno: 32 Broken pipeerrno: 33 Numerical argument out of domainerrno: 34 Numerical result out of rangeerrno: 35 Resource deadlock avoided errno: 36 File name too longerrno: 37 No locks available errno: 38 Function not implemented errno: 39 Directory not emptyerrno: 40 Too many levels of symbolic links errno: 41 Unknown error 41errno: 42 No message of desired typeerrno: 43 Identifier removed errno: 44 Channel number out of rangeerrno: 45 Level 2 not synchronized errno: 46 Level 3 halted errno: 47 Level 3 reseterrno: 48 Link number out of rangeerrno: 49 Protocol driver not attached errno: 50 No CSI structure available errno: 51 Level 2 halted errno: 52 Invalid exchangeerrno: 53 Invalid request descriptorerrno: 54 Exchange fullerrno: 55 No anode errno: 56 Invalid request code errno: 57 Invalid slot errno: 58 Unknown error 58errno: 59 Bad font file formaterrno: 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 errorerrno: 69 Srmount errorerrno: 70 Communication error on send errno: 71 Protocol errorerrno: 72 Multihop attempted errno: 73 RFS specific errorerrno: 74 Bad message errno: 75 Value too large for defined data typeerrno: 76 Name not unique on network errno: 77 File descriptor in bad state errno: 78 Remote address changederrno: 79 Can not access a needed shared libraryerrno: 80 Accessing a corrupted shared libraryerrno: 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 charactererrno: 85 Interrupted system call should be restarted errno: 86 Streams pipe errorerrno: 87 Too many userserrno: 88 Socket operation on non-socket errno: 89 Destination address requirederrno: 90 Message too longerrno: 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 useerrno: 99 Cannot assign requested address errno: 100 Network is down errno: 101 Network is unreachable errno: 102 Network dropped connection on reseterrno: 103 Software caused connection aborterrno: 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 shutdownerrno: 109 Too many references: cannot splice errno: 110 Connection timed outerrno: 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 fileerrno: 119 No XENIX semaphores available errno: 120 Is a named type fileerrno: 121 Remote I/O errorerrno: 122 Disk quota exceeded errno: 123 No medium founderrno: 124 Wrong medium typeerrno: 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-killerrno: 133 Memory page has hardware errorerrno: 134~255 unknown error!

Linux中，在头文件 /usr/include/asm-generic/errno-base.h 对基础常用errno进行了宏定义：

#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，对剩余的errno做了宏定义： #ifndef _ASM_GENERIC_ERRNO_H #define _ASM_GENERIC_ERRNO_H #include  #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

2. 打印错误信息

1). 打印错误信息 / perror

• 作用：
  打印系统错误信息

• 头文件：

  #include 

• 函数原型：

  void perror(const char *s)

• 参数：

  s: 字符串提示符

• 输出形式：
  const char *s: strerror(errno) //提示符：发生系统错误的原因

• 返回值：
  无返回值

2). 字符串显示错误信息 / strerror

• 作用：
  将错误码以字符串的信息显示出来

• 头文件：

  #include 

• 函数原型：

  char *strerror(int errnum);

• 参数：

  errnum: 即errno

• 返回值：
  返回错误码字符串信息

https://www.cnblogs.com/Jimmy1988/p/7485133.html

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