Returns true
if self
represents a Friday, false
otherwise:
t = Time.utc(2000, 1, 7) # => 2000-01-07 00:00:00 UTC t.friday? # => true
Related: Time#saturday?
, Time#sunday?
, Time#monday?
.
Returns status information for ios as an object of type File::Stat
.
f = File.new("testfile") s = f.stat "%o" % s.mode #=> "100644" s.blksize #=> 4096 s.atime #=> Wed Apr 09 08:53:54 CDT 2003
Opens the stream, writes the given data
to it, and closes the stream; returns the number of bytes written.
When called from class IO (but not subclasses of IO), this method has potential security vulnerabilities if called with untrusted input; see Command Injection.
The first argument must be a string; its meaning depends on whether it starts with the pipe character ('|'
):
If so (and if self
is IO), the rest of the string is a command to be executed as a subprocess.
Otherwise, the string is the path to a file.
With argument command
given, executes the command in a shell, passes data
through standard input, writes its output to $stdout, and returns the length of the given data
:
IO.write('| cat', 'Hello World!') # => 12
Output:
Hello World!
With argument path
given, writes the given data
to the file at that path:
IO.write('t.tmp', 'abc') # => 3 File.read('t.tmp') # => "abc"
If offset
is zero (the default), the file is overwritten:
IO.write('t.tmp', 'A') # => 1 File.read('t.tmp') # => "A"
If offset
in within the file content, the file is partly overwritten:
IO.write('t.tmp', 'abcdef') # => 3 File.read('t.tmp') # => "abcdef" # Offset within content. IO.write('t.tmp', '012', 2) # => 3 File.read('t.tmp') # => "ab012f"
If offset
is outside the file content, the file is padded with null characters "\u0000"
:
IO.write('t.tmp', 'xyz', 10) # => 3 File.read('t.tmp') # => "ab012f\u0000\u0000\u0000\u0000xyz"
Optional keyword arguments opts
specify:
Encoding options.
Behaves like IO.write
, except that the stream is opened in binary mode with ASCII-8BIT encoding.
When called from class IO (but not subclasses of IO), this method has potential security vulnerabilities if called with untrusted input; see Command Injection.
Creates a pair of pipe endpoints, read_io
and write_io
, connected to each other.
If argument enc_string
is given, it must be a string containing one of:
The name of the encoding to be used as the external encoding.
The colon-separated names of two encodings to be used as the external and internal encodings.
If argument int_enc
is given, it must be an Encoding
object or encoding name string that specifies the internal encoding to be used; if argument ext_enc
is also given, it must be an Encoding
object or encoding name string that specifies the external encoding to be used.
The string read from read_io
is tagged with the external encoding; if an internal encoding is also specified, the string is converted to, and tagged with, that encoding.
If any encoding is specified, optional hash arguments specify the conversion option.
Optional keyword arguments opts
specify:
Encoding Options.
With no block given, returns the two endpoints in an array:
IO.pipe # => [#<IO:fd 4>, #<IO:fd 5>]
With a block given, calls the block with the two endpoints; closes both endpoints and returns the value of the block:
IO.pipe {|read_io, write_io| p read_io; p write_io }
Output:
#<IO:fd 6> #<IO:fd 7>
Not available on all platforms.
In the example below, the two processes close the ends of the pipe that they are not using. This is not just a cosmetic nicety. The read end of a pipe will not generate an end of file condition if there are any writers with the pipe still open. In the case of the parent process, the rd.read
will never return if it does not first issue a wr.close
:
rd, wr = IO.pipe if fork wr.close puts "Parent got: <#{rd.read}>" rd.close Process.wait else rd.close puts 'Sending message to parent' wr.write "Hi Dad" wr.close end
produces:
Sending message to parent Parent got: <Hi Dad>
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.
Writes the given object
to self, which must be opened for writing (see Modes); returns the number bytes written. If object
is not a string is converted via method to_s:
f = File.new('t.tmp', 'w') f.syswrite('foo') # => 3 f.syswrite(30) # => 2 f.syswrite(:foo) # => 3 f.close
This methods should not be used with other stream-writer methods.
Behaves like IO#write
, except that it:
Writes 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), pwrite
allows multiple threads and processes to use the same IO object for writing at various offsets.
f = File.open('t.tmp', 'w+') # Write 6 bytes at offset 3. f.pwrite('ABCDEF', 3) # => 6 f.rewind f.read # => "\u0000\u0000\u0000ABCDEF" f.close
Not available on some platforms.
Writes each of the given objects
to self
, which must be opened for writing (see Access Modes); returns the total number bytes written; each of objects
that is not a string is converted via method to_s
:
$stdout.write('Hello', ', ', 'World!', "\n") # => 14 $stdout.write('foo', :bar, 2, "\n") # => 8
Output:
Hello, World! foobar2
Related: IO#read
.
Iterates over the elements of self
.
With a block given and no argument, calls the block each element of the range; returns self
:
a = [] (1..5).step {|element| a.push(element) } # => 1..5 a # => [1, 2, 3, 4, 5] a = [] ('a'..'e').step {|element| a.push(element) } # => "a".."e" a # => ["a", "b", "c", "d", "e"]
With a block given and a positive integer argument n
given, calls the block with element 0
, element n
, element 2n
, and so on:
a = [] (1..5).step(2) {|element| a.push(element) } # => 1..5 a # => [1, 3, 5] a = [] ('a'..'e').step(2) {|element| a.push(element) } # => "a".."e" a # => ["a", "c", "e"]
With no block given, returns an enumerator, which will be of class Enumerator::ArithmeticSequence
if self
is numeric; otherwise of class Enumerator:
e = (1..5).step(2) # => ((1..5).step(2)) e.class # => Enumerator::ArithmeticSequence ('a'..'e').step # => #<Enumerator: ...>
Related: Range#%
.
With no argument, returns the first element of self
, if it exists:
(1..4).first # => 1 ('a'..'d').first # => "a"
With non-negative integer argument n
given, returns the first n
elements in an array:
(1..10).first(3) # => [1, 2, 3] (1..10).first(0) # => [] (1..4).first(50) # => [1, 2, 3, 4]
Raises an exception if there is no first element:
(..4).first # Raises RangeError
With no argument, returns the last element of self
, if it exists:
(1..4).last # => 4 ('a'..'d').last # => "d"
Note that last
with no argument returns the end element of self
even if exclude_end?
is true
:
(1...4).last # => 4 ('a'...'d').last # => "d"
With non-negative integer argument n
given, returns the last n
elements in an array:
(1..10).last(3) # => [8, 9, 10] (1..10).last(0) # => [] (1..4).last(50) # => [1, 2, 3, 4]
Note that last
with argument does not return the end element of self
if exclude_end?
it true
:
(1...4).last(3) # => [1, 2, 3] ('a'...'d').last(3) # => ["a", "b", "c"]
Raises an exception if there is no last element:
(1..).last # Raises RangeError
Deletes every element that appears in the given enumerable object and returns self.
Callback invoked whenever a subclass of the current class is created.
Example:
class Foo def self.inherited(subclass) puts "New subclass: #{subclass}" end end class Bar < Foo end class Baz < Bar end
produces:
New subclass: Bar New subclass: Baz
Recursively deletes a directory, including all directories beneath it.
See FileUtils.rm_rf
See File.lstat
.