131 Linux Error Codes for C Programming Language using errno |
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Programmers should handle all kinds of errors to protect the program from failure. In C programming language, there is no direct support for error handling. You have to detect the failure and handle the error. In C programming language, return values represents success or failure. Inside a C program, when a function fails, you should handle the errors accordingly, or at least record the errors in a log file. When you are running some program on Linux environment, you might notice that it gives some error number. For example, “Error no is : 17”, which doesn’t really say much. You really need to know what error number 17 means. This article shows all available error numbers along with it descriptions. This article might be a handy reference for you, when you encounter an error number and you would like to know what it means. In C programming language, there is an external variable called “errno”. From this errno variable you can use some error handling functions to find out the error description and handle it appropriately. You have to include errno.h header file to use external variable errno. perror function prints error description in standard error. The strerror function returns a string describing the error code passed in the argument errnum.The following C code snippet tries to open a file through open system call. There are two flags in the open call. O_CREAT flag is to create a file, if the file does not exist. O_EXCL flag is used with O_CREAT, if the file is already exist open call will fail with the proper error number. $ cat fileopen.c #include #include #include #include main() { // Declaration of a file descriptor int fd; // Opening a file fd = open("/root/sasikala/testing",O_CREAT|O_EXCL); // If Open is failed if ( fd < 0 ) { printf("Opening file : Failed\n"); printf ("Error no is : %d\n", errno); printf("Error description is : %s\n",strerror(errno)); } // If Open is success else printf("Opening file : Success\n"); } $ cc -o fileopen fileopen.c $ ./fileopen Opening file : Success $ ./fileopen Opening file : Failed Error no is : 17 Error description is : File existsAt first execution, open got executed successfully, and it created the file since the file was not available. In next execution, it throws an error number 17, which is “File already exist”. The following table shows list of error numbers and its descriptions in Linux operation system ERROR CODE TABLE Error number Error Code Error Description 1 EPERM Operation not permitted 2 ENOENT No such file or directory 3 ESRCH No such process 4 EINTR Interrupted system call 5 EIO I/O error 6 ENXIO No such device or address 7 E2BIG Argument list too long 8 ENOEXEC Exec format error 9 EBADF Bad file number 10 ECHILD No child processes 11 EAGAIN Try again 12 ENOMEM Out of memory 13 EACCES Permission denied 14 EFAULT Bad address 15 ENOTBLK Block device required 16 EBUSY Device or resource busy 17 EEXIST File exists 18 EXDEV Cross-device link 19 ENODEV No such device 20 ENOTDIR Not a directory 21 EISDIR Is a directory 22 EINVAL Invalid argument 23 ENFILE File table overflow 24 EMFILE Too many open files 25 ENOTTY Not a typewriter 26 ETXTBSY Text file busy 27 EFBIG File too large 28 ENOSPC No space left on device 29 ESPIPE Illegal seek 30 EROFS Read-only file system 31 EMLINK Too many links 32 EPIPE Broken pipe 33 EDOM Math argument out of domain of func 34 ERANGE Math result not representable 35 EDEADLK Resource deadlock would occur 36 ENAMETOOLONG File name too long 37 ENOLCK No record locks available 38 ENOSYS Function not implemented 39 ENOTEMPTY Directory not empty 40 ELOOP Too many symbolic links encountered 42 ENOMSG No message of desired type 43 EIDRM Identifier removed 44 ECHRNG Channel number out of range 45 EL2NSYNC Level 2 not synchronized 46 EL3HLT Level 3 halted 47 EL3RST Level 3 reset 48 ELNRNG Link number out of range 49 EUNATCH Protocol driver not attached 50 ENOCSI No CSI structure available 51 EL2HLT Level 2 halted 52 EBADE Invalid exchange 53 EBADR Invalid request descriptor 54 EXFULL Exchange full 55 ENOANO No anode 56 EBADRQC Invalid request code 57 EBADSLT Invalid slot 59 EBFONT Bad font file format 60 ENOSTR Device not a stream 61 ENODATA No data available 62 ETIME Timer expired 63 ENOSR Out of streams resources 64 ENONET Machine is not on the network 65 ENOPKG Package not installed 66 EREMOTE Object is remote 67 ENOLINK Link has been severed 68 EADV Advertise error 69 ESRMNT Srmount error 70 ECOMM Communication error on send 71 EPROTO Protocol error 72 EMULTIHOP Multihop attempted 73 EDOTDOT RFS specific error 74 EBADMSG Not a data message 75 EOVERFLOW Value too large for defined data type 76 ENOTUNIQ Name not unique on network 77 EBADFD File descriptor in bad state 78 EREMCHG Remote address changed 79 ELIBACC Can not access a needed shared library 80 ELIBBAD Accessing a corrupted shared library 81 ELIBSCN .lib section in a.out corrupted 82 ELIBMAX Attempting to link in too many shared libraries 83 ELIBEXEC Cannot exec a shared library directly 84 EILSEQ Illegal byte sequence 85 ERESTART Interrupted system call should be restarted 86 ESTRPIPE Streams pipe error 87 EUSERS Too many users 88 ENOTSOCK Socket operation on non-socket 89 EDESTADDRREQ Destination address required 90 EMSGSIZE Message too long 91 EPROTOTYPE Protocol wrong type for socket 92 ENOPROTOOPT Protocol not available 93 EPROTONOSUPPORT Protocol not supported 94 ESOCKTNOSUPPORT Socket type not supported 95 EOPNOTSUPP Operation not supported on transport endpoint 96 EPFNOSUPPORT Protocol family not supported 97 EAFNOSUPPORT Address family not supported by protocol 98 EADDRINUSE Address already in use 99 EADDRNOTAVAIL Cannot assign requested address 100 ENETDOWN Network is down 101 ENETUNREACH Network is unreachable 102 ENETRESET Network dropped connection because of reset 103 ECONNABORTED Software caused connection abort 104 ECONNRESET Connection reset by peer 105 ENOBUFS No buffer space available 106 EISCONN Transport endpoint is already connected 107 ENOTCONN Transport endpoint is not connected 108 ESHUTDOWN Cannot send after transport endpoint shutdown 109 ETOOMANYREFS Too many references: cannot splice 110 ETIMEDOUT Connection timed out 111 ECONNREFUSED Connection refused 112 EHOSTDOWN Host is down 113 EHOSTUNREACH No route to host 114 EALREADY Operation already in progress 115 EINPROGRESS Operation now in progress 116 ESTALE Stale NFS file handle 117 EUCLEAN Structure needs cleaning 118 ENOTNAM Not a XENIX named type file 119 ENAVAIL No XENIX semaphores available 120 EISNAM Is a named type file 121 EREMOTEIO Remote I/O error 122 EDQUOT Quota exceeded 123 ENOMEDIUM No medium found 124 EMEDIUMTYPE Wrong medium type 125 ECANCELED Operation Canceled 126 ENOKEY Required key not available 127 EKEYEXPIRED Key has expired 128 EKEYREVOKED Key has been revoked 129 EKEYREJECTED Key was rejected by service 130 EOWNERDEAD Owner died 131 ENOTRECOVERABLE State not recoverableWhen you see an error number thrown by a C program on a Linux environment, you might find the above table handy to identify what those error number means. 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