GNU Info
(libc.info)Error Codes
Error Codes
===========
The error code macros are defined in the header file `errno.h'. All
of them expand into integer constant values. Some of these error codes
can't occur on the GNU system, but they can occur using the GNU library
on other systems.
- Macro: int EPERM
Operation not permitted; only the owner of the file (or other
resource) or processes with special privileges can perform the
operation.
- Macro: int ENOENT
No such file or directory. This is a "file doesn't exist" error
for ordinary files that are referenced in contexts where they are
expected to already exist.
- Macro: int ESRCH
No process matches the specified process ID.
- Macro: int EINTR
Interrupted function call; an asynchronous signal occurred and
prevented completion of the call. When this happens, you should
try the call again.
You can choose to have functions resume after a signal that is
handled, rather than failing with `EINTR'; see Note: Interrupted
Primitives.
- Macro: int EIO
Input/output error; usually used for physical read or write errors.
- Macro: int ENXIO
No such device or address. The system tried to use the device
represented by a file you specified, and it couldn't find the
device. This can mean that the device file was installed
incorrectly, or that the physical device is missing or not
correctly attached to the computer.
- Macro: int E2BIG
Argument list too long; used when the arguments passed to a new
program being executed with one of the `exec' functions (Note:
Executing a File) occupy too much memory space. This condition
never arises in the GNU system.
- Macro: int ENOEXEC
Invalid executable file format. This condition is detected by the
`exec' functions; see Note: Executing a File.
- Macro: int EBADF
Bad file descriptor; for example, I/O on a descriptor that has been
closed or reading from a descriptor open only for writing (or vice
versa).
- Macro: int ECHILD
There are no child processes. This error happens on operations
that are supposed to manipulate child processes, when there aren't
any processes to manipulate.
- Macro: int EDEADLK
Deadlock avoided; allocating a system resource would have resulted
in a deadlock situation. The system does not guarantee that it
will notice all such situations. This error means you got lucky
and the system noticed; it might just hang. Note: File Locks,
for an example.
- Macro: int ENOMEM
No memory available. The system cannot allocate more virtual
memory because its capacity is full.
- Macro: int EACCES
Permission denied; the file permissions do not allow the attempted
operation.
- Macro: int EFAULT
Bad address; an invalid pointer was detected. In the GNU system,
this error never happens; you get a signal instead.
- Macro: int ENOTBLK
A file that isn't a block special file was given in a situation
that requires one. For example, trying to mount an ordinary file
as a file system in Unix gives this error.
- Macro: int EBUSY
Resource busy; a system resource that can't be shared is already
in use. For example, if you try to delete a file that is the root
of a currently mounted filesystem, you get this error.
- Macro: int EEXIST
File exists; an existing file was specified in a context where it
only makes sense to specify a new file.
- Macro: int EXDEV
An attempt to make an improper link across file systems was
detected. This happens not only when you use `link' (Note: Hard
Links) but also when you rename a file with `rename' (Note:
Renaming Files).
- Macro: int ENODEV
The wrong type of device was given to a function that expects a
particular sort of device.
- Macro: int ENOTDIR
A file that isn't a directory was specified when a directory is
required.
- Macro: int EISDIR
File is a directory; you cannot open a directory for writing, or
create or remove hard links to it.
- Macro: int EINVAL
Invalid argument. This is used to indicate various kinds of
problems with passing the wrong argument to a library function.
- Macro: int EMFILE
The current process has too many files open and can't open any
more. Duplicate descriptors do count toward this limit.
In BSD and GNU, the number of open files is controlled by a
resource limit that can usually be increased. If you get this
error, you might want to increase the `RLIMIT_NOFILE' limit or
make it unlimited; Note: Limits on Resources.
- Macro: int ENFILE
There are too many distinct file openings in the entire system.
Note that any number of linked channels count as just one file
opening; see Note: Linked Channels. This error never occurs in
the GNU system.
- Macro: int ENOTTY
Inappropriate I/O control operation, such as trying to set terminal
modes on an ordinary file.
- Macro: int ETXTBSY
An attempt to execute a file that is currently open for writing, or
write to a file that is currently being executed. Often using a
debugger to run a program is considered having it open for writing
and will cause this error. (The name stands for "text file
busy".) This is not an error in the GNU system; the text is
copied as necessary.
- Macro: int EFBIG
File too big; the size of a file would be larger than allowed by
the system.
- Macro: int ENOSPC
No space left on device; write operation on a file failed because
the disk is full.
- Macro: int ESPIPE
Invalid seek operation (such as on a pipe).
- Macro: int EROFS
An attempt was made to modify something on a read-only file system.
- Macro: int EMLINK
Too many links; the link count of a single file would become too
large. `rename' can cause this error if the file being renamed
already has as many links as it can take (Note: Renaming Files).
- Macro: int EPIPE
Broken pipe; there is no process reading from the other end of a
pipe. Every library function that returns this error code also
generates a `SIGPIPE' signal; this signal terminates the program
if not handled or blocked. Thus, your program will never actually
see `EPIPE' unless it has handled or blocked `SIGPIPE'.
- Macro: int EDOM
Domain error; used by mathematical functions when an argument
value does not fall into the domain over which the function is
defined.
- Macro: int ERANGE
Range error; used by mathematical functions when the result value
is not representable because of overflow or underflow.
- Macro: int EAGAIN
Resource temporarily unavailable; the call might work if you try
again later. The macro `EWOULDBLOCK' is another name for `EAGAIN';
they are always the same in the GNU C library.
This error can happen in a few different situations:
* An operation that would block was attempted on an object that
has non-blocking mode selected. Trying the same operation
again will block until some external condition makes it
possible to read, write, or connect (whatever the operation).
You can use `select' to find out when the operation will be
possible; Note: Waiting for I/O.
*Portability Note:* In many older Unix systems, this condition
was indicated by `EWOULDBLOCK', which was a distinct error
code different from `EAGAIN'. To make your program portable,
you should check for both codes and treat them the same.
* A temporary resource shortage made an operation impossible.
`fork' can return this error. It indicates that the shortage
is expected to pass, so your program can try the call again
later and it may succeed. It is probably a good idea to
delay for a few seconds before trying it again, to allow time
for other processes to release scarce resources. Such
shortages are usually fairly serious and affect the whole
system, so usually an interactive program should report the
error to the user and return to its command loop.
- Macro: int EWOULDBLOCK
In the GNU C library, this is another name for `EAGAIN' (above).
The values are always the same, on every operating system.
C libraries in many older Unix systems have `EWOULDBLOCK' as a
separate error code.
- Macro: int EINPROGRESS
An operation that cannot complete immediately was initiated on an
object that has non-blocking mode selected. Some functions that
must always block (such as `connect'; Note: Connecting) never
return `EAGAIN'. Instead, they return `EINPROGRESS' to indicate
that the operation has begun and will take some time. Attempts to
manipulate the object before the call completes return `EALREADY'.
You can use the `select' function to find out when the pending
operation has completed; Note: Waiting for I/O.
- Macro: int EALREADY
An operation is already in progress on an object that has
non-blocking mode selected.
- Macro: int ENOTSOCK
A file that isn't a socket was specified when a socket is required.
- Macro: int EMSGSIZE
The size of a message sent on a socket was larger than the
supported maximum size.
- Macro: int EPROTOTYPE
The socket type does not support the requested communications
protocol.
- Macro: int ENOPROTOOPT
You specified a socket option that doesn't make sense for the
particular protocol being used by the socket. Note: Socket
Options.
- Macro: int EPROTONOSUPPORT
The socket domain does not support the requested communications
protocol (perhaps because the requested protocol is completely
invalid). Note: Creating a Socket.
- Macro: int ESOCKTNOSUPPORT
The socket type is not supported.
- Macro: int EOPNOTSUPP
The operation you requested is not supported. Some socket
functions don't make sense for all types of sockets, and others
may not be implemented for all communications protocols. In the
GNU system, this error can happen for many calls when the object
does not support the particular operation; it is a generic
indication that the server knows nothing to do for that call.
- Macro: int EPFNOSUPPORT
The socket communications protocol family you requested is not
supported.
- Macro: int EAFNOSUPPORT
The address family specified for a socket is not supported; it is
inconsistent with the protocol being used on the socket. Note:
Sockets.
- Macro: int EADDRINUSE
The requested socket address is already in use. Note: Socket
Addresses.
- Macro: int EADDRNOTAVAIL
The requested socket address is not available; for example, you
tried to give a socket a name that doesn't match the local host
name. Note: Socket Addresses.
- Macro: int ENETDOWN
A socket operation failed because the network was down.
- Macro: int ENETUNREACH
A socket operation failed because the subnet containing the remote
host was unreachable.
- Macro: int ENETRESET
A network connection was reset because the remote host crashed.
- Macro: int ECONNABORTED
A network connection was aborted locally.
- Macro: int ECONNRESET
A network connection was closed for reasons outside the control of
the local host, such as by the remote machine rebooting or an
unrecoverable protocol violation.
- Macro: int ENOBUFS
The kernel's buffers for I/O operations are all in use. In GNU,
this error is always synonymous with `ENOMEM'; you may get one or
the other from network operations.
- Macro: int EISCONN
You tried to connect a socket that is already connected. Note:
Connecting.
- Macro: int ENOTCONN
The socket is not connected to anything. You get this error when
you try to transmit data over a socket, without first specifying a
destination for the data. For a connectionless socket (for
datagram protocols, such as UDP), you get `EDESTADDRREQ' instead.
- Macro: int EDESTADDRREQ
No default destination address was set for the socket. You get
this error when you try to transmit data over a connectionless
socket, without first specifying a destination for the data with
`connect'.
- Macro: int ESHUTDOWN
The socket has already been shut down.
- Macro: int ETOOMANYREFS
???
- Macro: int ETIMEDOUT
A socket operation with a specified timeout received no response
during the timeout period.
- Macro: int ECONNREFUSED
A remote host refused to allow the network connection (typically
because it is not running the requested service).
- Macro: int ELOOP
Too many levels of symbolic links were encountered in looking up a
file name. This often indicates a cycle of symbolic links.
- Macro: int ENAMETOOLONG
Filename too long (longer than `PATH_MAX'; Note: Limits for
Files) or host name too long (in `gethostname' or `sethostname';
Note: Host Identification).
- Macro: int EHOSTDOWN
The remote host for a requested network connection is down.
- Macro: int EHOSTUNREACH
The remote host for a requested network connection is not
reachable.
- Macro: int ENOTEMPTY
Directory not empty, where an empty directory was expected.
Typically, this error occurs when you are trying to delete a
directory.
- Macro: int EPROCLIM
This means that the per-user limit on new process would be
exceeded by an attempted `fork'. Note: Limits on Resources, for
details on the `RLIMIT_NPROC' limit.
- Macro: int EUSERS
The file quota system is confused because there are too many users.
- Macro: int EDQUOT
The user's disk quota was exceeded.
- Macro: int ESTALE
Stale NFS file handle. This indicates an internal confusion in
the NFS system which is due to file system rearrangements on the
server host. Repairing this condition usually requires unmounting
and remounting the NFS file system on the local host.
- Macro: int EREMOTE
An attempt was made to NFS-mount a remote file system with a file
name that already specifies an NFS-mounted file. (This is an
error on some operating systems, but we expect it to work properly
on the GNU system, making this error code impossible.)
- Macro: int EBADRPC
???
- Macro: int ERPCMISMATCH
???
- Macro: int EPROGUNAVAIL
???
- Macro: int EPROGMISMATCH
???
- Macro: int EPROCUNAVAIL
???
- Macro: int ENOLCK
No locks available. This is used by the file locking facilities;
see Note: File Locks. This error is never generated by the GNU
system, but it can result from an operation to an NFS server
running another operating system.
- Macro: int EFTYPE
Inappropriate file type or format. The file was the wrong type
for the operation, or a data file had the wrong format.
On some systems `chmod' returns this error if you try to set the
sticky bit on a non-directory file; Note: Setting Permissions.
- Macro: int EAUTH
???
- Macro: int ENEEDAUTH
???
- Macro: int ENOSYS
Function not implemented. This indicates that the function called
is not implemented at all, either in the C library itself or in the
operating system. When you get this error, you can be sure that
this particular function will always fail with `ENOSYS' unless you
install a new version of the C library or the operating system.
- Macro: int ENOTSUP
Not supported. A function returns this error when certain
parameter values are valid, but the functionality they request is
not available. This can mean that the function does not implement
a particular command or option value or flag bit at all. For
functions that operate on some object given in a parameter, such
as a file descriptor or a port, it might instead mean that only
_that specific object_ (file descriptor, port, etc.) is unable to
support the other parameters given; different file descriptors
might support different ranges of parameter values.
If the entire function is not available at all in the
implementation, it returns `ENOSYS' instead.
- Macro: int EILSEQ
While decoding a multibyte character the function came along an
invalid or an incomplete sequence of bytes or the given wide
character is invalid.
- Macro: int EBACKGROUND
In the GNU system, servers supporting the `term' protocol return
this error for certain operations when the caller is not in the
foreground process group of the terminal. Users do not usually
see this error because functions such as `read' and `write'
translate it into a `SIGTTIN' or `SIGTTOU' signal. Note: Job
Control, for information on process groups and these signals.
- Macro: int EDIED
In the GNU system, opening a file returns this error when the file
is translated by a program and the translator program dies while
starting up, before it has connected to the file.
- Macro: int ED
The experienced user will know what is wrong.
- Macro: int EGREGIOUS
You did *what*?
- Macro: int EIEIO
Go home and have a glass of warm, dairy-fresh milk.
- Macro: int EGRATUITOUS
This error code has no purpose.
- Macro: int EBADMSG
- Macro: int EIDRM
- Macro: int EMULTIHOP
- Macro: int ENODATA
- Macro: int ENOLINK
- Macro: int ENOMSG
- Macro: int ENOSR
- Macro: int ENOSTR
- Macro: int EOVERFLOW
- Macro: int EPROTO
- Macro: int ETIME
_The following error codes are defined by the Linux/i386 kernel.
They are not yet documented._
- Macro: int ERESTART
- Macro: int ECHRNG
- Macro: int EL2NSYNC
- Macro: int EL3HLT
- Macro: int EL3RST
- Macro: int ELNRNG
- Macro: int EUNATCH
- Macro: int ENOCSI
- Macro: int EL2HLT
- Macro: int EBADE
- Macro: int EBADR
- Macro: int EXFULL
- Macro: int ENOANO
- Macro: int EBADRQC
- Macro: int EBADSLT
- Macro: int EDEADLOCK
- Macro: int EBFONT
- Macro: int ENONET
- Macro: int ENOPKG
- Macro: int EADV
- Macro: int ESRMNT
- Macro: int ECOMM
- Macro: int EDOTDOT
- Macro: int ENOTUNIQ
- Macro: int EBADFD
- Macro: int EREMCHG
- Macro: int ELIBACC
- Macro: int ELIBBAD
- Macro: int ELIBSCN
- Macro: int ELIBMAX
- Macro: int ELIBEXEC
- Macro: int ESTRPIPE
- Macro: int EUCLEAN
- Macro: int ENOTNAM
- Macro: int ENAVAIL
- Macro: int EISNAM
- Macro: int EREMOTEIO
- Macro: int ENOMEDIUM
- Macro: int EMEDIUMTYPE
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