In C programming language, <errno.h> is a header that's part of the C standard library.
It defines all the ENAME constants used to name errors and gives access to the global int errno;.
Standard POSIX errors:
E2BIG EACCES EADDRINUSE EADDRNOTAVAIL EAFNOSUPPORT EAGAIN EALREADY EBADF EBADMSG EBUSY ECANCELED ECHILD ECONNABORTED ECONNREFUSED ECONNRESET EDEADLK EDESTADDRREQ EDOM EDQUOT EEXIST EFAULT EFBIG EHOSTUNREACH EIDRM EILSEQ EINPROGRESS EINTR EINVAL EIO EISCONN EISDIR ELOOP EMFILE EMLINK EMSGSIZE EMULTIHOP ENAMETOOLONG ENETDOWN ENETRESET ENETUNREACH ENFILE ENOBUFS ENODATA ENODEV ENOENT ENOEXEC ENOLCK ENOLINK ENOMEM ENOMSG ENOPROTOOPT ENOSPC ENOSR ENOSTR ENOSYS ENOTCONN ENOTDIR ENOTEMPTY ENOTRECOVERABLE ENOTSOCK ENOTSUP ENOTTY ENXIO EOPNOTSUPP EOVERFLOW EOWNERDEAD EPERM EPIPE EPROTO EPROTONOSUPPORT EPROTOTYPE ERANGE EROFS ESPIPE ESRCH ESTALE ETIME ETIMEDOUT ETXTBSY EWOULDBLOCK EXDEV
C99 specific errors:
EDOM EILSEQ ERANGE
Other / linux errors:
EBADE EBADFD EBADR EBADRQC EBADSLT ECHRNG ECOMM EDEADLOCK EHOSTDOWN EHWPOISON EISNAM EKEYEXPIRED EKEYREJECTED EKEYREVOKED EL2HLT EL2NSYNC EL3HLT EL3RST ELIBACC ELIBBAD ELIBMAX ELIBSCN ELIBEXEC ELNRNG EMEDIUMTYPE ENOANO ENOKEY ENOMEDIUM ENONET ENOPKG ENOTBLK ENOTUNIQ EPFNOSUPPORT EREMCHG EREMOTE EREMOTEIO ERESTART ERFKILL ESHUTDOWN ESOCKTNOSUPPORT ESTRPIPE ETOOMANYREFS EUCLEAN EUNATCH EUSERS EXFULL