Linux错误处理与错误号

 来源：ChinaUnix博客 作者：huntley_bian 编辑：周荣茂

每天只要进步一点点!

    小知识:

    linux从文本界面启动:

     首先进入root权限，在fedora下，终端输入:su root;输入你的密码；进入root权限下，使用shell，vi /etc/inittab,修改inittab文件，把id:5:initdefault的5改成3。其他几种对应的模式如下： 0 关机 1 单用户模式 2 多用户模式，但是不支持网络访问 3 多用户模式，文本模式启动 4 无定义的 5 图形化界面 6 重启

     进入图形界面startx,就OK了,当然前提是装了图形界面

    

    文件权限:

    4:读 相当于r

    2:写 相当于w

    1:执行 相当二x

    常用7 可读可写可执行

     6 可读可写

     5 可读可执行

     4 只可读

    

    Linux错误机制

    1,在用户进行文件操作的时候,会出各种各样的错误,比如权限不足,空间不足,找不到文件等,此时需在程序中设置错误捕捉语句,并显示错误.

     在linux中错误定义成了错误号和错误常数,如果发生错误,便宜会返回

    

     在终端上可以用以下命令来查看错误的定义:

     cat /usr/include/asm/errno.h

     如下:

    #ifndef _I386_ERRNO_H

    #define _I386_ERRNO_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 /* Arg 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 */

    #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 NFS 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 */

    #endif

    通过strerror函数来显示错误信息

    输入以下程序:

    #include

    #include

    #include /*包含错误处理的头文件*/

    int main(void)

    {

     printf("ENOENT:\n");

     char *mesg = strerror(ENOENT);

     printf(" Errno :%d\n",ENOENT);

     printf(" Message:%s\n",mesg);

     printf("EIO :\n");

     char *mesg1 = strerror(EIO);

     printf(" Errno :%d\n",EIO);

     printf(" Message:%s\n",mesg1);

     printf("EEXIST :\n");

     char *mesg2 = strerror(EEXIST);

     printf(" Errno :%d\n",EEXIST);

     printf(" Message:%s\n",mesg2);

    }

    编译运行结果如下:

    ENOENT:

     Errno :2

     Message:No such file or directory

    EIO :

     Errno :5

     Message:Input/output error

    EEXIST :

     Errno :17

     Message:File exists

    下面用序号显示错误信息

    char *strerrno(int erronum)

    输入以下源程序:

    #include

    #include

    #include

    int main(void)

    {

     int i;

     for(i=0;i

    编译运行如下:

    errno :0

    message :Success

    errno :1

    message :Operation not permitted

    errno :2

    message :No such file or directory

    errno :3

    message :No such process

    errno :4

    message :Interrupted system call

    errno :5

    message :Input/output error

    errno :6

    message :No such device or address

    errno :7

    message :Argument list too long

    errno :8

    message :Exec format error

    errno :9

    message :Bad file descriptor

    errno :10

    message :No child processes

    errno :11

    message :Resource temporarily unavailable

    errno :12

    message :Cannot allocate memory

    errno :13

    message :Permission denied

    errno :14

    message :Bad address

    errno :15

    message :Block device required