Displayed by `Errno.constants.each {|errno| err = Errno.const_get(errno); puts "#{err}: #{err.new.message}" }`

Errno in Ruby

Errno::ENOSYS: Function not implemented
Errno::EDESTADDRREQ: Destination address required
Errno::ESHUTDOWN: Can't send after socket shutdown
Errno::ENODEV: Operation not supported by device
Errno::ENOMEM: Cannot allocate memory
Errno::EMLINK: Too many links
Errno::EPROTO: Protocol error
Errno::ENETUNREACH: Network is unreachable
Errno::EIO: Input/output error
Errno::EMFILE: Too many open files
Errno::EIDRM: Identifier removed
Errno::ESOCKTNOSUPPORT: Socket type not supported
Errno::EHOSTUNREACH: No route to host
Errno::EEXIST: File exists
Errno::ENAMETOOLONG: File name too long
Errno::EUSERS: Too many users
Errno::EISCONN: Socket is already connected
Errno::EADDRNOTAVAIL: Can't assign requested address
Errno::ECHILD: No child processes
Errno::ESPIPE: Illegal seek
Errno::EREMOTE: Too many levels of remote in path
Errno::ENOPROTOOPT: Protocol not available
Errno::ECONNREFUSED: Connection refused
Errno::ESRCH: No such process
Errno::EINVAL: Invalid argument
Errno::EAGAIN: Resource temporarily unavailable
Errno::ERANGE: Result too large
Errno::EOVERFLOW: Value too large to be stored in data type
Errno::ECONNRESET: Connection reset by peer
Errno::ENOTBLK: Block device required
Errno::EFBIG: File too large
Errno::ETIME: STREAM ioctl timeout
Errno::EAFNOSUPPORT: Address family not supported by protocol family
Errno::ESTALE: Stale NFS file handle
Errno::ENOEXEC: Exec format error
Errno::EPERM: Operation not permitted
Errno::ENOTDIR: Not a directory
Errno::ENOTEMPTY: Directory not empty
Errno::EMSGSIZE: Message too long
Errno::ETOOMANYREFS: Too many references: can't splice
Errno::EACCES: Permission denied
Errno::EPIPE: Broken pipe
Errno::EMULTIHOP: EMULTIHOP (Reserved)
Errno::ENETRESET: Network dropped connection on reset
Errno::EALREADY: Operation already in progress
Errno::ENXIO: Device not configured
Errno::ENOTTY: Inappropriate ioctl for device
Errno::ENOSTR: Not a STREAM
Errno::EOPNOTSUPP: Operation not supported on socket
Errno::ENOTSOCK: Socket operation on non-socket
Errno::ENOTCONN: Socket is not connected
Errno::EXDEV: Cross-device link
Errno::ENOLCK: No locks available
Errno::ENOLINK: ENOLINK (Reserved)
Errno::ENETDOWN: Network is down
Errno::EAGAIN: Resource temporarily unavailable
Errno::EROFS: Read-only file system
Errno::ENFILE: Too many open files in system
Errno::ENOMSG: No message of desired type
Errno::EPROTONOSUPPORT: Protocol not supported
Errno::EHOSTDOWN: Host is down
Errno::EINTR: Interrupted system call
Errno::EBUSY: Resource busy
Errno::EDEADLK: Resource deadlock avoided
Errno::EILSEQ: Illegal byte sequence
Errno::ENOBUFS: No buffer space available
Errno::ENOSR: No STREAM resources
Errno::ENOSPC: No space left on device
Errno::EBADF: Bad file descriptor
Errno::EADDRINUSE: Address already in use
Errno::EDQUOT: Disc quota exceeded
Errno::EPROTOTYPE: Protocol wrong type for socket
Errno::ELOOP: Too many levels of symbolic links
Errno::EISDIR: Is a directory
Errno::ENOENT: No such file or directory
Errno::ETIMEDOUT: Operation timed out
Errno::EBADMSG: Bad message
Errno::EDOM: Numerical argument out of domain
Errno::EFAULT: Bad address
Errno::ECONNABORTED: Software caused connection abort
Errno::ETXTBSY: Text file busy
Errno::E2BIG: Argument list too long
Errno::EPFNOSUPPORT: Protocol family not supported
Errno::ENODATA: No message available on STREAM
Errno::EINPROGRESS: Operation now in progress