errno.h(7POSIX) POSIX Programmer's Manual errno.h(7POSIX)
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of
this interface may differ (consult the corresponding Linux manual page for details of
Linux behavior), or the interface may not be implemented on Linux.
errno.h — system error numbers
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 POSIX.1‐2008 defers to the ISO C standard.
The ISO C standard only requires the symbols [EDOM], [EILSEQ], and [ERANGE] to be defined.
The <errno.h> header shall provide a declaration or definition for errno. The symbol
errno shall expand to a modifiable lvalue of type int. It is unspecified whether errno is
a macro or an identifier declared with external linkage. If a macro definition is sup‐
pressed in order to access an actual object, or a program defines an identifier with the
name errno, the behavior is undefined.
The <errno.h> header shall define the following macros which shall expand to integer con‐
stant expressions with type int, distinct positive values (except as noted below), and
which shall be suitable for use in #if preprocessing directives:
E2BIG Argument list too long.
EACCES Permission denied.
Address in use.
Address not available.
Address family not supported.
EAGAIN Resource unavailable, try again (may be the same value as [EWOULDBLOCK]).
Connection already in progress.
EBADF Bad file descriptor.
EBUSY Device or resource busy.
ECHILD No child processes.
Resource deadlock would occur.
Destination address required.
EDOM Mathematics argument out of domain of function.
EEXIST File exists.
EFAULT Bad address.
EFBIG File too large.
Host is unreachable.
EIDRM Identifier removed.
EILSEQ Illegal byte sequence.
Operation in progress.
EINTR Interrupted function.
EINVAL Invalid argument.
EIO I/O error.
Socket is connected.
EISDIR Is a directory.
ELOOP Too many levels of symbolic links.
EMFILE File descriptor value too large.
EMLINK Too many links.
Message too large.
Filename too long.
Network is down.
Connection aborted by network.
ENFILE Too many files open in system.
No buffer space available.
No message is available on the STREAM head read queue.
ENODEV No such device.
ENOENT No such file or directory.
Executable file format error.
ENOLCK No locks available.
ENOMEM Not enough space.
ENOMSG No message of the desired type.
Protocol not available.
ENOSPC No space left on device.
ENOSR No STREAM resources.
ENOSTR Not a STREAM.
ENOSYS Function not supported.
The socket is not connected.
Not a directory or a symbolic link to a directory.
Directory not empty.
State not recoverable.
Not a socket.
Not supported (may be the same value as [EOPNOTSUPP]).
ENOTTY Inappropriate I/O control operation.
ENXIO No such device or address.
Operation not supported on socket (may be the same value as [ENOTSUP]).
Value too large to be stored in data type.
Previous owner died.
EPERM Operation not permitted.
EPIPE Broken pipe.
EPROTO Protocol error.
Protocol not supported.
Protocol wrong type for socket.
ERANGE Result too large.
EROFS Read-only file system.
ESPIPE Invalid seek.
ESRCH No such process.
ETIME Stream ioctl() timeout.
Connection timed out.
Text file busy.
Operation would block (may be the same value as [EAGAIN]).
EXDEV Cross-device link.
The following sections are informative.
Additional error numbers may be defined on conforming systems; see the System Interfaces
volume of POSIX.1‐2008.
The System Interfaces volume of POSIX.1‐2008, Section 2.3, Error Numbers
Portions of this text are reprinted and reproduced in electronic form from IEEE Std
1003.1, 2013 Edition, Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the event of any discrep‐
ancy between this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original Standard can be
obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are most likely to have
been introduced during the conversion of the source files to man page format. To report
such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 errno.h(7POSIX)