1#@!#!123s

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Filename : popen-c.ri
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U:RDoc::AnyMethod[iI"
popen:ETI"IO::popen;TT:publico:RDoc::Markup::Document:@parts[Ho:RDoc::Markup::Paragraph;	[I"6Executes the given command +cmd+ as a subprocess ;TI"Awhose $stdin and $stdout are connected to a new stream +io+.;To:RDoc::Markup::BlankLine�o;
;	[I"XThis method has potential security vulnerabilities if called with untrusted input; ;TI">see {Command Injection}[rdoc-ref:command_injection.rdoc].;T@o;
;	[I"3If no block is given, returns the new stream, ;TI"Pwhich depending on given +mode+ may be open for reading, writing, or both. ;TI"QThe stream should be explicitly closed (eventually) to avoid resource leaks.;T@o;
;	[	I"<If a block is given, the stream is passed to the block ;TI"2(again, open for reading, writing, or both); ;TI"1when the block exits, the stream is closed, ;TI"Sand the block's value is assigned to global variable <tt>$?</tt> and returned.;T@o;
;	[I"9Optional argument +mode+ may be any valid \IO mode. ;TI"4See {Access Modes}[rdoc-ref:File@Access+Modes].;T@o;
;	[I"FRequired argument +cmd+ determines which of the following occurs:;T@o:RDoc::Markup::List:
@type:BULLET:@items[	o:RDoc::Markup::ListItem:@label0;	[o;
;	[I"The process forks.;To;;0;	[o;
;	[I")A specified program runs in a shell.;To;;0;	[o;
;	[I"7A specified program runs with specified arguments.;To;;0;	[o;
;	[I"OA specified program runs with specified arguments and a specified +argv0+.;T@o;
;	[I"%Each of these is detailed below.;T@o;
;	[I"VThe optional hash argument +env+ specifies name/value pairs that are to be added ;TI"5to the environment variables for the subprocess:;T@o:RDoc::Markup::Verbatim;	[
I"8IO.popen({'FOO' => 'bar'}, 'ruby', 'r+') do |pipe|
;TI"#  pipe.puts 'puts ENV["FOO"]'
;TI"  pipe.close_write
;TI"  pipe.gets
;TI"end => "bar\n"
;T:@format0o;
;	[I"/Optional keyword arguments +opts+ specify:;T@o;;
;;[o;;0;	[o;
;	[I".{Open options}[rdoc-ref:IO@Open+Options].;To;;0;	[o;
;	[I"B{Encoding options}[rdoc-ref:encodings.rdoc@Encoding+Options].;To;;0;	[o;
;	[I"Options for Kernel#spawn.;T@o;
;	[I"<b>Forked \Process</b>;T@o;
;	[I"\When argument +cmd+ is the 1-character string <tt>'-'</tt>, causes the process to fork:;To;;	[I"IO.popen('-') do |pipe|
;TI"  if pipe
;TI">    $stderr.puts "In parent, child pid is #{pipe.pid}\n"
;TI"  else
;TI"1    $stderr.puts "In child, pid is #{$$}\n"
;TI"  end
;TI"	end
;T;0o;
;	[I"Output:;T@o;;	[I"#In parent, child pid is 26253
;TI"In child, pid is 26253
;T;0o;
;	[I"6Note that this is not supported on all platforms.;T@o;
;	[I"<b>Shell Subprocess</b>;T@o;
;	[I"DWhen argument +cmd+ is a single string (but not <tt>'-'</tt>), ;TI"7the program named +cmd+ is run as a shell command:;T@o;;	[I"!IO.popen('uname') do |pipe|
;TI"  pipe.readlines
;TI"	end
;T;0o;
;	[I"Output:;T@o;;	[I"["Linux\n"]
;T;0o;
;	[I"Another example:;T@o;;	[
I")IO.popen('/bin/sh', 'r+') do |pipe|
;TI"  pipe.puts('ls')
;TI"  pipe.close_write
;TI"(  $stderr.puts pipe.readlines.size
;TI"	end
;T;0o;
;	[I"Output:;T@o;;	[I"	213
;T;0o;
;	[I"<b>Program Subprocess</b>;T@o;
;	[I"1When argument +cmd+ is an array of strings, ;TI"Zthe program named <tt>cmd[0]</tt> is run with all elements of +cmd+ as its arguments:;T@o;;	[I"+IO.popen(['du', '..', '.']) do |pipe|
;TI"(  $stderr.puts pipe.readlines.size
;TI"	end
;T;0o;
;	[I"Output:;T@o;;	[I"
1111
;T;0o;
;	[I"2<b>Program Subprocess with <tt>argv0</tt></b>;T@o;
;	[I"UWhen argument +cmd+ is an array whose first element is a 2-element string array ;TI"7and whose remaining elements (if any) are strings:;T@o;;
;;[o;;0;	[o;
;	[I"d<tt>cmd[0][0]</tt> (the first string in the nested array) is the name of a program that is run.;To;;0;	[o;
;	[I"i<tt>cmd[0][1]</tt> (the second string in the nested array) is set as the program's <tt>argv[0]</tt>.;To;;0;	[o;
;	[I"V<tt>cmd[1..-1]</tt> (the strings in the outer array) are the program's arguments.;T@o;
;	[I")Example (sets <tt>$0</tt> to 'foo'):;T@o;;	[I"GIO.popen([['/bin/sh', 'foo'], '-c', 'echo $0']).read # => "foo\n"
;T;0o;
;	[I"!<b>Some Special Examples</b>;T@o;;	[I"# Set IO encoding.
;TI"IIO.popen("nkf -e filename", :external_encoding=>"EUC-JP") {|nkf_io|
;TI"#  euc_jp_string = nkf_io.read
;TI"}
;TI"
;TI"]# Merge standard output and standard error using Kernel#spawn option. See Kernel#spawn.
;TI"9IO.popen(["ls", "/", :err=>[:child, :out]]) do |io|
;TI"&  ls_result_with_error = io.read
;TI"	end
;TI"
;TI"4# Use mixture of spawn options and IO options.
;TI"9IO.popen(["ls", "/"], :err=>[:child, :out]) do |io|
;TI"&  ls_result_with_error = io.read
;TI"	end
;TI"
;TI" f = IO.popen("uname")
;TI" p f.readlines
;TI" f.close
;TI"& puts "Parent is #{Process.pid}"
;TI"* IO.popen("date") {|f| puts f.gets }
;TI"S IO.popen("-") {|f| $stderr.puts "#{Process.pid} is here, f is #{f.inspect}"}
;TI" p $?
;TI"? IO.popen(%w"sed -e s|^|<foo>| -e s&$&;zot;&", "r+") {|f|
;TI"1   f.puts "bar"; f.close_write; puts f.gets
;TI" }
;T;0o;
;	[I" Output (from last section):;T@o;;	[I"["Linux\n"]
;TI"Parent is 21346
;TI""Thu Jan 15 22:41:19 JST 2009
;TI"$21346 is here, f is #<IO:fd 3>
;TI"21352 is here, f is nil
;TI"*#<Process::Status: pid 21352 exit 0>
;TI"<foo>bar;zot;
;T;0o;
;	[I";Raises exceptions that IO.pipe and Kernel.spawn raise.;T:
@fileI"	io.c;T:0@omit_headings_from_table_of_contents_below0I"yIO.popen(env = {}, cmd, mode = 'r', **opts) -> io
IO.popen(env = {}, cmd, mode = 'r', **opts) {|io| ... } -> object
;T0[�I"(*args);T@�FI"IO;TcRDoc::NormalClass00