Returns true if key is pressed. key may be a virtual key code or its name (String or Symbol) with out “VK_” prefix.
This method is Windows only.
You must require ‘io/console’ to use this method.
Returns true if an IO object is in non-blocking mode.
Enables non-blocking mode on a stream when set to true, and blocking mode when set to false.
This method set or clear O_NONBLOCK flag for the file descriptor in ios.
The behavior of most IO methods is not affected by this flag because they retry system calls to complete their task after EAGAIN and partial read/write. (An exception is IO#syswrite which doesn’t retry.)
This method can be used to clear non-blocking mode of standard I/O. Since nonblocking methods (read_nonblock, etc.) set non-blocking mode but they doesn’t clear it, this method is usable as follows.
END { STDOUT.nonblock = false } STDOUT.write_nonblock("foo")
Since the flag is shared across processes and many non-Ruby commands doesn’t expect standard I/O with non-blocking mode, it would be safe to clear the flag before Ruby program exits.
For example following Ruby program leaves STDIN/STDOUT/STDER non-blocking mode. (STDIN, STDOUT and STDERR are connected to a terminal. So making one of them nonblocking-mode effects other two.) Thus cat command try to read from standard input and it causes “Resource temporarily unavailable” error (EAGAIN).
% ruby -e '
STDOUT.write_nonblock("foo\n")'; cat
foo
cat: -: Resource temporarily unavailable
Clearing the flag makes the behavior of cat command normal. (cat command waits input from standard input.)
% ruby -rio/nonblock -e '
END { STDOUT.nonblock = false }
STDOUT.write_nonblock("foo")
'; cat
foo
Yields self in non-blocking mode.
When false is given as an argument, self is yielded in blocking mode. The original mode is restored after the block is executed.
Writes the given objects to the stream; returns nil. Appends the output record separator $OUTPUT_RECORD_SEPARATOR ($\), if it is not nil. See Line IO.
With argument objects given, for each object:
Converts via its method to_s if not a string.
Writes to the stream.
If not the last object, writes the output field separator $OUTPUT_FIELD_SEPARATOR ($,) if it is not nil.
With default separators:
f = File.open('t.tmp', 'w+') objects = [0, 0.0, Rational(0, 1), Complex(0, 0), :zero, 'zero'] p $OUTPUT_RECORD_SEPARATOR p $OUTPUT_FIELD_SEPARATOR f.print(*objects) f.rewind p f.read f.close
Output:
nil nil "00.00/10+0izerozero"
With specified separators:
$\ = "\n" $, = ',' f.rewind f.print(*objects) f.rewind p f.read
Output:
"0,0.0,0/1,0+0i,zero,zero\n"
With no argument given, writes the content of $_ (which is usually the most recent user input):
f = File.open('t.tmp', 'w+') gets # Sets $_ to the most recent user input. f.print f.close
Formats and writes objects to the stream.
For details on format_string, see Format Specifications.
Behaves like IO#readpartial, except that it:
Reads at the given offset (in bytes).
Disregards, and does not modify, the stream’s position (see Position).
Bypasses any user space buffering in the stream.
Because this method does not disturb the stream’s state (its position, in particular), pread allows multiple threads and processes to use the same IO object for reading at various offsets.
f = File.open('t.txt') f.read # => "First line\nSecond line\n\nFourth line\nFifth line\n" f.pos # => 52 # Read 12 bytes at offset 0. f.pread(12, 0) # => "First line\n" # Read 9 bytes at offset 8. f.pread(9, 8) # => "ne\nSecon" f.close
Not available on some platforms.
Invokes Posix system call ioctl(2), which issues a low-level command to an I/O device.
Issues a low-level command to an I/O device. The arguments and returned value are platform-dependent. The effect of the call is platform-dependent.
If argument argument is an integer, it is passed directly; if it is a string, it is interpreted as a binary sequence of bytes.
Not implemented on all platforms.
Returns rat rounded to the nearest value with a precision of ndigits decimal digits (default: 0).
When the precision is negative, the returned value is an integer with at least ndigits.abs trailing zeros.
Returns a rational when ndigits is positive, otherwise returns an integer.
Rational(3).round #=> 3 Rational(2, 3).round #=> 1 Rational(-3, 2).round #=> -2 # decimal - 1 2 3 . 4 5 6 # ^ ^ ^ ^ ^ ^ # precision -3 -2 -1 0 +1 +2 Rational('-123.456').round(+1).to_f #=> -123.5 Rational('-123.456').round(-1) #=> -120
The optional half keyword argument is available similar to Float#round.
Rational(25, 100).round(1, half: :up) #=> (3/10) Rational(25, 100).round(1, half: :down) #=> (1/5) Rational(25, 100).round(1, half: :even) #=> (1/5) Rational(35, 100).round(1, half: :up) #=> (2/5) Rational(35, 100).round(1, half: :down) #=> (3/10) Rational(35, 100).round(1, half: :even) #=> (2/5) Rational(-25, 100).round(1, half: :up) #=> (-3/10) Rational(-25, 100).round(1, half: :down) #=> (-1/5) Rational(-25, 100).round(1, half: :even) #=> (-1/5)
Allocates space for a new object of class’s class and does not call initialize on the new instance. The returned object must be an instance of class.
klass = Class.new do def initialize(*args) @initialized = true end def initialized? @initialized || false end end klass.allocate.initialized? #=> false
Enters exclusive section and executes the block. Leaves the exclusive section automatically when the block exits. See example under MonitorMixin.
Predicate method for root directories. Returns true if the pathname consists of consecutive slashes.
It doesn’t access the filesystem. So it may return false for some pathnames which points to roots such as /usr/...
Receives up to maxlen bytes from socket. flags is zero or more of the MSG_ options. The first element of the results, mesg, is the data received. The second element, sender_addrinfo, contains protocol-specific address information of the sender.
maxlen - the maximum number of bytes to receive from the socket
flags - zero or more of the MSG_ options
# In one file, start this first require 'socket' include Socket::Constants socket = Socket.new( AF_INET, SOCK_STREAM, 0 ) sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' ) socket.bind( sockaddr ) socket.listen( 5 ) client, client_addrinfo = socket.accept data = client.recvfrom( 20 )[0].chomp puts "I only received 20 bytes '#{data}'" sleep 1 socket.close # In another file, start this second require 'socket' include Socket::Constants socket = Socket.new( AF_INET, SOCK_STREAM, 0 ) sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' ) socket.connect( sockaddr ) socket.puts "Watch this get cut short!" socket.close
On unix-based based systems the following system exceptions may be raised if the call to recvfrom fails:
Errno::EAGAIN - the socket file descriptor is marked as O_NONBLOCK and no data is waiting to be received; or MSG_OOB is set and no out-of-band data is available and either the socket file descriptor is marked as O_NONBLOCK or the socket does not support blocking to wait for out-of-band-data
Errno::EWOULDBLOCK - see Errno::EAGAIN
Errno::EBADF - the socket is not a valid file descriptor
Errno::ECONNRESET - a connection was forcibly closed by a peer
Errno::EFAULT - the socket’s internal buffer, address or address length cannot be accessed or written
Errno::EINTR - a signal interrupted recvfrom before any data was available
Errno::EINVAL - the MSG_OOB flag is set and no out-of-band data is available
Errno::EIO - an i/o error occurred while reading from or writing to the filesystem
Errno::ENOBUFS - insufficient resources were available in the system to perform the operation
Errno::ENOMEM - insufficient memory was available to fulfill the request
Errno::ENOSR - there were insufficient STREAMS resources available to complete the operation
Errno::ENOTCONN - a receive is attempted on a connection-mode socket that is not connected
Errno::ENOTSOCK - the socket does not refer to a socket
Errno::EOPNOTSUPP - the specified flags are not supported for this socket type
Errno::ETIMEDOUT - the connection timed out during connection establishment or due to a transmission timeout on an active connection
On Windows systems the following system exceptions may be raised if the call to recvfrom fails:
Errno::ENETDOWN - the network is down
Errno::EFAULT - the internal buffer and from parameters on socket are not part of the user address space, or the internal fromlen parameter is too small to accommodate the peer address
Errno::EINTR - the (blocking) call was cancelled by an internal call to the WinSock function WSACancelBlockingCall
Errno::EINPROGRESS - a blocking Windows Sockets 1.1 call is in progress or the service provider is still processing a callback function
Errno::EINVAL - socket has not been bound with a call to bind, or an unknown flag was specified, or MSG_OOB was specified for a socket with SO_OOBINLINE enabled, or (for byte stream-style sockets only) the internal len parameter on socket was zero or negative
Errno::EISCONN - socket is already connected. The call to recvfrom is not permitted with a connected socket on a socket that is connection oriented or connectionless.
Errno::ENETRESET - the connection has been broken due to the keep-alive activity detecting a failure while the operation was in progress.
Errno::EOPNOTSUPP - MSG_OOB was specified, but socket is not stream-style such as type SOCK_STREAM. OOB data is not supported in the communication domain associated with socket, or socket is unidirectional and supports only send operations
Errno::ESHUTDOWN - socket has been shutdown. It is not possible to call recvfrom on a socket after shutdown has been invoked.
Errno::EWOULDBLOCK - socket is marked as nonblocking and a call to recvfrom would block.
Errno::EMSGSIZE - the message was too large to fit into the specified buffer and was truncated.
Errno::ETIMEDOUT - the connection has been dropped, because of a network failure or because the system on the other end went down without notice
Errno::ECONNRESET - the virtual circuit was reset by the remote side executing a hard or abortive close. The application should close the socket; it is no longer usable. On a UDP-datagram socket this error indicates a previous send operation resulted in an ICMP Port Unreachable message.
Creates a pair of sockets connected each other.
domain should be a communications domain such as: :INET, :INET6, :UNIX, etc.
socktype should be a socket type such as: :STREAM, :DGRAM, :RAW, etc.
protocol should be a protocol defined in the domain, defaults to 0 for the domain.
s1, s2 = Socket.pair(:UNIX, :STREAM, 0) s1.send "a", 0 s1.send "b", 0 s1.close p s2.recv(10) #=> "ab" p s2.recv(10) #=> "" p s2.recv(10) #=> "" s1, s2 = Socket.pair(:UNIX, :DGRAM, 0) s1.send "a", 0 s1.send "b", 0 p s2.recv(10) #=> "a" p s2.recv(10) #=> "b"
Sets a socket option. These are protocol and system specific, see your local system documentation for details.
level is an integer, usually one of the SOL_ constants such as Socket::SOL_SOCKET, or a protocol level. A string or symbol of the name, possibly without prefix, is also accepted.
optname is an integer, usually one of the SO_ constants, such as Socket::SO_REUSEADDR. A string or symbol of the name, possibly without prefix, is also accepted.
optval is the value of the option, it is passed to the underlying setsockopt() as a pointer to a certain number of bytes. How this is done depends on the type:
Integer: value is assigned to an int, and a pointer to the int is passed, with length of sizeof(int).
true or false: 1 or 0 (respectively) is assigned to an int, and the int is passed as for an Integer. Note that false must be passed, not nil.
String: the string’s data and length is passed to the socket.
socketoption is an instance of Socket::Option
Some socket options are integers with boolean values, in this case setsockopt could be called like this:
sock.setsockopt(:SOCKET, :REUSEADDR, true) sock.setsockopt(Socket::SOL_SOCKET,Socket::SO_REUSEADDR, true) sock.setsockopt(Socket::Option.bool(:INET, :SOCKET, :REUSEADDR, true))
Some socket options are integers with numeric values, in this case setsockopt could be called like this:
sock.setsockopt(:IP, :TTL, 255) sock.setsockopt(Socket::IPPROTO_IP, Socket::IP_TTL, 255) sock.setsockopt(Socket::Option.int(:INET, :IP, :TTL, 255))
Option values may be structs. Passing them can be complex as it involves examining your system headers to determine the correct definition. An example is an ip_mreq, which may be defined in your system headers as:
struct ip_mreq { struct in_addr imr_multiaddr; struct in_addr imr_interface; };
In this case setsockopt could be called like this:
optval = IPAddr.new("224.0.0.251").hton + IPAddr.new(Socket::INADDR_ANY, Socket::AF_INET).hton sock.setsockopt(Socket::IPPROTO_IP, Socket::IP_ADD_MEMBERSHIP, optval)
Gets a socket option. These are protocol and system specific, see your local system documentation for details. The option is returned as a Socket::Option object.
level is an integer, usually one of the SOL_ constants such as Socket::SOL_SOCKET, or a protocol level. A string or symbol of the name, possibly without prefix, is also accepted.
optname is an integer, usually one of the SO_ constants, such as Socket::SO_REUSEADDR. A string or symbol of the name, possibly without prefix, is also accepted.
Some socket options are integers with boolean values, in this case getsockopt could be called like this:
reuseaddr = sock.getsockopt(:SOCKET, :REUSEADDR).bool optval = sock.getsockopt(Socket::SOL_SOCKET,Socket::SO_REUSEADDR) optval = optval.unpack "i" reuseaddr = optval[0] == 0 ? false : true
Some socket options are integers with numeric values, in this case getsockopt could be called like this:
ipttl = sock.getsockopt(:IP, :TTL).int optval = sock.getsockopt(Socket::IPPROTO_IP, Socket::IP_TTL) ipttl = optval.unpack1("i")
Option values may be structs. Decoding them can be complex as it involves examining your system headers to determine the correct definition. An example is a +struct linger+, which may be defined in your system headers as:
struct linger { int l_onoff; int l_linger; };
In this case getsockopt could be called like this:
# Socket::Option knows linger structure. onoff, linger = sock.getsockopt(:SOCKET, :LINGER).linger optval = sock.getsockopt(Socket::SOL_SOCKET, Socket::SO_LINGER) onoff, linger = optval.unpack "ii" onoff = onoff == 0 ? false : true
Returns the local address of the socket as a sockaddr string.
TCPServer.open("127.0.0.1", 15120) {|serv| p serv.getsockname #=> "\x02\x00;\x10\x7F\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00" }
If Addrinfo object is preferred over the binary string, use BasicSocket#local_address.
Receives a message and return the message as a string and an address which the message come from.
maxlen is the maximum number of bytes to receive.
flags should be a bitwise OR of Socket::MSG_* constants.
ipaddr is the same as IPSocket#{peeraddr,addr}.
u1 = UDPSocket.new u1.bind("127.0.0.1", 4913) u2 = UDPSocket.new u2.send "uuuu", 0, "127.0.0.1", 4913 p u1.recvfrom(10) #=> ["uuuu", ["AF_INET", 33230, "localhost", "127.0.0.1"]]
returns the socket type as an integer.
Addrinfo.tcp("localhost", 80).socktype == Socket::SOCK_STREAM #=> true
Receives a message via unixsocket.
maxlen is the maximum number of bytes to receive.
flags should be a bitwise OR of Socket::MSG_* constants.
outbuf will contain only the received data after the method call even if it is not empty at the beginning.
s1 = Socket.new(:UNIX, :DGRAM, 0) s1_ai = Addrinfo.unix("/tmp/sock1") s1.bind(s1_ai) s2 = Socket.new(:UNIX, :DGRAM, 0) s2_ai = Addrinfo.unix("/tmp/sock2") s2.bind(s2_ai) s3 = UNIXSocket.for_fd(s2.fileno) s1.send "a", 0, s2_ai p s3.recvfrom(10) #=> ["a", ["AF_UNIX", "/tmp/sock1"]]
Creates a pair of sockets connected to each other.
type should be a socket type such as: :STREAM, :DGRAM, :RAW, etc.
protocol should be a protocol defined in the domain. 0 is default protocol for the domain.
s1, s2 = UNIXSocket.pair s1.send "a", 0 s1.send "b", 0 p s2.recv(10) #=> "ab"
See IO#pread.