NAME

errno.h - system error numbers

SYNOPSIS

#include <errno.h>

DESCRIPTION

^[CX] Some of the functionality described on this reference page extends the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers to the ISO C standard.

^[CX] The ISO C standard only requires the symbols [EDOM], [EILSEQ], and [ERANGE] to be defined.

The <errno.h> header shall provide a declaration for errno and give positive values for the following symbolic constants. Their values shall be unique except as noted below.

[E2BIG]

Argument list too long.

[EACCES]

Permission denied.

[EADDRINUSE]

Address in use.

[EADDRNOTAVAIL]

Address not available.

[EAFNOSUPPORT]

Address family not supported.

[EAGAIN]

Resource unavailable, try again (may be the same value as [EWOULDBLOCK]).

[EALREADY]

Connection already in progress.

[EBADF]

Bad file descriptor.

[EBADMSG]

Bad message.

[EBUSY]

Device or resource busy.

[ECANCELED]

Operation canceled.

[ECHILD]

No child processes.

[ECONNABORTED]

Connection aborted.

[ECONNREFUSED]

Connection refused.

[ECONNRESET]

Connection reset.

[EDEADLK]

Resource deadlock would occur.

[EDESTADDRREQ]

Destination address required.

[EDOM]

Mathematics argument out of domain of function.

[EDQUOT]

Reserved.

[EEXIST]

File exists.

[EFAULT]

Bad address.

[EFBIG]

File too large.

[EHOSTUNREACH]

Host is unreachable.

[EIDRM]

Identifier removed.

[EILSEQ]

Illegal byte sequence.

[EINPROGRESS]

Operation in progress.

[EINTR]

Interrupted function.

[EINVAL]

Invalid argument.

[EIO]

I/O error.

[EISCONN]

Socket is connected.

[EISDIR]

Is a directory.

[ELOOP]

Too many levels of symbolic links.

[EMFILE]

Too many open files.

[EMLINK]

Too many links.

[EMSGSIZE]

Message too large.

[EMULTIHOP]

Reserved.

[ENAMETOOLONG]

Filename too long.

[ENETDOWN]

Network is down.

[ENETRESET]

Connection aborted by network.

[ENETUNREACH]

Network unreachable.

[ENFILE]

Too many files open in system.

[ENOBUFS]

No buffer space available.

[ENODATA]

^[XSR] No message is available on the STREAM head read queue.

[ENODEV]

No such device.

[ENOENT]

No such file or directory.

[ENOEXEC]

Executable file format error.

[ENOLCK]

No locks available.

[ENOLINK]

Reserved.

[ENOMEM]

Not enough space.

[ENOMSG]

No message of the desired type.

[ENOPROTOOPT]

Protocol not available.

[ENOSPC]

No space left on device.

[ENOSR]

^[XSR] No STREAM resources.

[ENOSTR]

^[XSR] Not a STREAM.

[ENOSYS]

Function not supported.

[ENOTCONN]

The socket is not connected.

[ENOTDIR]

Not a directory.

[ENOTEMPTY]

Directory not empty.

[ENOTSOCK]

Not a socket.

[ENOTSUP]

Not supported.

[ENOTTY]

Inappropriate I/O control operation.

[ENXIO]

No such device or address.

[EOPNOTSUPP]

Operation not supported on socket.

[EOVERFLOW]

Value too large to be stored in data type.

[EPERM]

Operation not permitted.

[EPIPE]

Broken pipe.

[EPROTO]

Protocol error.

[EPROTONOSUPPORT]

Protocol not supported.

[EPROTOTYPE]

Protocol wrong type for socket.

[ERANGE]

Result too large.

[EROFS]

Read-only file system.

[ESPIPE]

Invalid seek.

[ESRCH]

No such process.

[ESTALE]

Reserved.

[ETIME]

^[XSR] Stream ioctl() timeout.

[ETIMEDOUT]

Connection timed out.

[ETXTBSY]

Text file busy.

[EWOULDBLOCK]

Operation would block (may be the same value as [EAGAIN]).

[EXDEV]

Cross-device link.

APPLICATION USAGE

Additional error numbers may be defined on conforming systems; see the System Interfaces volume of IEEE Std 1003.1-2001.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

The System Interfaces volume of IEEE Std 1003.1-2001, Section 2.3, Error Numbers

CHANGE HISTORY

First released in Issue 1. Derived from Issue 1 of the SVID.

Issue 5

Updated for alignment with the POSIX Realtime Extension.

Issue 6

The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:

• The majority of the error conditions previously marked as extensions are now mandatory, except for the STREAMS-related error conditions.

Values for errno are now required to be distinct positive values rather than non-zero values. This change is for alignment with the ISO/IEC 9899:1999 standard.