errno.h man page

Prolog

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

Synopsis

#include <errno.h>

Description

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 suppressed 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 constant 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.
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
File descriptor value too large.
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
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
No STREAM resources.
ENOSTR
Not a STREAM.
ENOSYS
Function not supported.
ENOTCONN
The socket is not connected.
ENOTDIR
Not a directory or a symbolic link to a directory.
ENOTEMPTY
Directory not empty.
ENOTRECOVERABLE
State not recoverable.
ENOTSOCK
Not a socket.
ENOTSUP
Not supported (may be the same value as [EOPNOTSUPP]).
ENOTTY
Inappropriate I/O control operation.
ENXIO
No such device or address.
EOPNOTSUPP
Operation not supported on socket (may be the same value as [ENOTSUP]).
EOVERFLOW
Value too large to be stored in data type.
EOWNERDEAD
Previous owner died.
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
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.

The following sections are informative.

Application Usage

Additional error numbers may be defined on conforming systems; see the System Interfaces volume of POSIX.1‐2008.

See Also

The System Interfaces volume of POSIX.1‐2008, Section 2.3, Error Numbers

Info

2013 IEEE/The Open Group POSIX Programmer's Manual