errno description (error codes) in Linux
Linux errno description
errno – number of last error. If your program exits with non-zero exit code, it means it exited with error.
If you know the error code that is good. If you don’t know the error code then it is tough to debug. Following are the errno of Linux system calls. These will help you to debug the program.
DESCRIPTION from man Page
The <errno.h> header file defines the integer variable errno, which is set by system calls and some library func‐
tions in the event of an error to indicate what went wrong. Its value is significant only when the return value of
the call indicated an error (i.e., -1 from most system calls; -1 or NULL from most library functions); a function
that succeeds is allowed to change errno.
Valid error numbers are all nonzero; errno is never set to zero by any system call or library function.
For some system calls and library functions (e.g., getpriority(2)), -1 is a valid return on success. In such cases,
a successful return can be distinguished from an error return by setting errno to zero before the call, and then, if
the call returns a status that indicates that an error may have occurred, checking to see if errno has a nonzero
value.
errno is defined by the ISO C standard to be a modifiable lvalue of type int, and must not be explicitly declared;
errno may be a macro. errno is thread-local; setting it in one thread does not affect its value in any other
thread.
| ERRNO Macro | errno | errno description |
| EDEADLK | 35 | /* Resource deadlock would occur */ |
| ENAMETOOLONG | 36 | /* File name too long */ |
| ENOLCK | 37 | /* No record locks available */ |
| ENOSYS | 38 | /* Function not implemented */ |
| ENOTEMPTY | 39 | /* Directory not empty */ |
| ELOOP | 40 | /* Too many symbolic links encountered */ |
| EWOULDBLOCK / EAGAIN | /* Operation would block */ | |
| ENOMSG | 42 | /* No message of desired type */ |
| EIDRM | 43 | /* Identifier removed */ |
| ECHRNG | 44 | /* Channel number out of range */ |
| EL2NSYNC | 45 | /* Level 2 not synchronized */ |
| EL3HLT | 46 | /* Level 3 halted */ |
| EL3RST | 47 | /* Level 3 reset */ |
| ELNRNG | 48 | /* Link number out of range */ |
| EUNATCH | 49 | /* Protocol driver not attached */ |
| ENOCSI | 50 | /* No CSI structure available */ |
| EL2HLT | 51 | /* Level 2 halted */ |
| EBADE | 52 | /* Invalid exchange */ |
| EBADR | 53 | /* Invalid request descriptor */ |
| EXFULL | 54 | /* Exchange full */ |
| ENOANO | 55 | /* No anode */ |
| EBADRQC | 56 | /* Invalid request code */ |
| EBADSLT | 57 | /* Invalid slot */ |
| EDEADLOCK / EDEADLK | EDEADLK | |
| EBFONT | 59 | /* Bad font file format */ |
| ENOSTR | 60 | /* Device not a stream */ |
| ENODATA | 61 | /* No data available */ |
| ETIME | 62 | /* Timer expired */ |
| ENOSR | 63 | /* Out of streams resources */ |
| ENONET | 64 | /* Machine is not on the network */ |
| ENOPKG | 65 | /* Package not installed */ |
| EREMOTE | 66 | /* Object is remote */ |
| ENOLINK | 67 | /* Link has been severed */ |
| EADV | 68 | /* Advertise error */ |
| ESRMNT | 69 | /* Srmount error */ |
| ECOMM | 70 | /* Communication error on send */ |
| EPROTO | 71 | /* Protocol error */ |
| EMULTIHOP | 72 | /* Multihop attempted */ |
| EDOTDOT | 73 | /* RFS specific error */ |
| EBADMSG | 74 | /* Not a data message */ |
| EOVERFLOW | 75 | /* Value too large for defined data type */ |
| ENOTUNIQ | 76 | /* Name not unique on network */ |
| EBADFD | 77 | /* File descriptor in bad state */ |
| EREMCHG | 78 | /* Remote address changed */ |
| ELIBACC | 79 | /* Can not access a needed shared library */ |
| ELIBBAD | 80 | /* Accessing a corrupted shared library */ |
| ELIBSCN | 81 | /* .lib section in a.out corrupted */ |
| ELIBMAX | 82 | /* Attempting to link in too many shared libraries */ |
| ELIBEXEC | 83 | /* Cannot exec a shared library directly */ |
| EILSEQ | 84 | /* Illegal byte sequence */ |
| ERESTART | 85 | /* Interrupted system call should be restarted */ |
| ESTRPIPE | 86 | /* Streams pipe error */ |
| EUSERS | 87 | /* Too many users */ |
| ENOTSOCK | 88 | /* Socket operation on non-socket */ |
| EDESTADDRREQ | 89 | /* Destination address required */ |
| EMSGSIZE | 90 | /* Message too long */ |
| EPROTOTYPE | 91 | /* Protocol wrong type for socket */ |
| ENOPROTOOPT | 92 | /* Protocol not available */ |
| EPROTONOSUPPORT | 93 | /* Protocol not supported */ |
| ESOCKTNOSUPPORT | 94 | /* Socket type not supported */ |
| EOPNOTSUPP | 95 | /* Operation not supported on transport endpoint */ |
| EPFNOSUPPORT | 96 | /* Protocol family not supported */ |
| EAFNOSUPPORT | 97 | /* Address family not supported by protocol */ |
| EADDRINUSE | 98 | /* Address already in use */ |
| EADDRNOTAVAIL | 99 | /* Cannot assign requested address */ |
| ENETDOWN | 100 | /* Network is down */ |
| ENETUNREACH | 101 | /* Network is unreachable */ |
| ENETRESET | 102 | /* Network dropped connection because of reset */ |
| ECONNABORTED | 103 | /* Software caused connection abort */ |
| ECONNRESET | 104 | /* Connection reset by peer */ |
| ENOBUFS | 105 | /* No buffer space available */ |
| EISCONN | 106 | /* Transport endpoint is already connected */ |
| ENOTCONN | 107 | /* Transport endpoint is not connected */ |
| ESHUTDOWN | 108 | /* Cannot send after transport endpoint shutdown */ |
| ETOOMANYREFS | 109 | /* Too many references: cannot splice */ |
| ETIMEDOUT | 110 | /* Connection timed out */ |
| ECONNREFUSED | 111 | /* Connection refused */ |
| EHOSTDOWN | 112 | /* Host is down */ |
| EHOSTUNREACH | 113 | /* No route to host */ |
| EALREADY | 114 | /* Operation already in progress */ |
| EINPROGRESS | 115 | /* Operation now in progress */ |
| ESTALE | 116 | /* Stale file handle */ |
| EUCLEAN | 117 | /* Structure needs cleaning */ |
| ENOTNAM | 118 | /* Not a XENIX named type file */ |
| ENAVAIL | 119 | /* No XENIX semaphores available */ |
| EISNAM | 120 | /* Is a named type file */ |
| EREMOTEIO | 121 | /* Remote I/O error */ |
| EDQUOT | 122 | /* Quota exceeded */ |
| ENOMEDIUM | 123 | /* No medium found */ |
| EMEDIUMTYPE | 124 | /* Wrong medium type */ |
| ECANCELED | 125 | /* Operation Canceled */ |
| ENOKEY | 126 | /* Required key not available */ |
| EKEYEXPIRED | 127 | /* Key has expired */ |
| EKEYREVOKED | 128 | /* Key has been revoked */ |
| EKEYREJECTED | 129 | /* Key was rejected by service */ |
| /* for robust mutexes */ | ||
| EOWNERDEAD | 130 | /* Owner died */ |
| ENOTRECOVERABLE | 131 | /* State not recoverable */ |
| ERFKILL | 132 | /* Operation not possible due to RF-kill */ |
| EHWPOISON | 133 | /* Memory page has hardware error */ |