The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2004 Edition
Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.
A newer edition of this document exists here


errno.h - system error numbers


#include <errno.h>


[CX] [Option Start] 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. [Option End]

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

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.

Argument list too long.
Permission denied.
Address in use.
Address not available.
Address family not supported.
Resource unavailable, try again (may be the same value as [EWOULDBLOCK]).
Connection already in progress.
Bad file descriptor.
Bad message.
Device or resource busy.
Operation canceled.
No child processes.
Connection aborted.
Connection refused.
Connection reset.
Resource deadlock would occur.
Destination address required.
Mathematics argument out of domain of function.
File exists.
Bad address.
File too large.
Host is unreachable.
Identifier removed.
Illegal byte sequence.
Operation in progress.
Interrupted function.
Invalid argument.
I/O error.
Socket is connected.
Is a directory.
Too many levels of symbolic links.
Too many open files.
Too many links.
Message too large.
Filename too long.
Network is down.
Connection aborted by network.
Network unreachable.
Too many files open in system.
No buffer space available.
[XSR] [Option Start] No message is available on the STREAM head read queue. [Option End]
No such device.
No such file or directory.
Executable file format error.
No locks available.
Not enough space.
No message of the desired type.
Protocol not available.
No space left on device.
[XSR] [Option Start] No STREAM resources. [Option End]
[XSR] [Option Start] Not a STREAM. [Option End]
Function not supported.
The socket is not connected.
Not a directory.
Directory not empty.
Not a socket.
Not supported.
Inappropriate I/O control operation.
No such device or address.
Operation not supported on socket.
Value too large to be stored in data type.
Operation not permitted.
Broken pipe.
Protocol error.
Protocol not supported.
Protocol wrong type for socket.
Result too large.
Read-only file system.
Invalid seek.
No such process.
[XSR] [Option Start] Stream ioctl() timeout. [Option End]
Connection timed out.
Text file busy.
Operation would block (may be the same value as [EAGAIN]).
Cross-device link.

The following sections are informative.


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






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


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:

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.

End of informative text.

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