ERRNO (3) | C library functions | Unix Manual Pages

SYNOPSIS

DESCRIPTION

The integer errno is set by system calls (and some library functions) to indicate what went wrong. Its value is significant only when the call returned an error (usually -1), and a library function that does succeed is allowed to change errno.

Sometimes, when -1 is also a legal return value one has to zero errno before the call in order to detect possible errors.

errno is defined by the ISO C standard to be a modifiable lvalue of type int, and must not be explicitly declared; errno may be a macro. errno is thread-local; setting it in one thread does not affect its value in any other thread.

Valid error numbers are all non-zero; errno is never set to zero by any library function. All the error names specified by POSIX.1 must have distinct values.

POSIX.1 (2001 edition) lists the following symbolic error names. Of these, EDOM and ERANGE are in the ISO C standard. ISO C Amendment 1 defines the additional error number EILSEQ for coding errors in multibyte or wide characters.

E2BIG	Arg list too long
EACCES	Permission denied
EADDRINUSE
	Address in use
EADDRNOTAVAIL
	Address not available
EAFNOSUPPORT
	Address family not supported
EAGAIN	Resource temporarily unavailable
EALREADY
	Connection already in progress
EBADF	Bad file descriptor
EBADMSG
	Bad message
EBUSY	Resource busy
ECANCELED
	Operation canceled
ECHILD	No child processes
ECONNABORTED
	Connection aborted
ECONNREFUSED
	Connection refused
ECONNRESET
	Connection reset
EDEADLK
	Resource deadlock avoided
EDESTADDRREQ
	Destination address required
EDOM	Domain error
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 call
EINVAL	Invalid argument
EIO	Input/output 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
	Inappropriate message buffer length
EMULTIHOP
	Reserved
ENAMETOOLONG
	Filename too long
ENETDOWN
	Network is down
ENETRESET
	Connection aborted by network
ENETUNREACH
	Network unreachable
ENFILE	Too many open files 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
	Exec 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 implemented
ENOTCON
	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	STREAM ioctl() timeout
ETIMEDOUT
	Operation timed out
ETXTBSY
	Test file busy
EWOULDBLOCK
	Operation would block (may be same value as EAGAIN)
EXDEV	Improper link

"SEE ALSO"

perror(3), strerror(3)

Created by Blin Media, 2008-2013

NAME

CONTENTS

SYNOPSIS

DESCRIPTION

"SEE ALSO"