Standard streams

<h2 id="application">Application</h2>

<p>Users generally know standard streams as input and output channels that handle data coming from an input device, or that write data from the application. The data may be text with any encoding, or <a href="/facts/Binary_file/ysttM8hh">binary data</a>.
When a program is run as a <a href="/facts/Daemon_(computing)/bzuEVGGX">daemon</a>, its standard error stream is redirected into a log file, typically for error analysis purposes.
</p><p>Streams may be used to chain applications, meaning that the output stream of one program can be redirected to be the input stream to another application. In many operating systems this is expressed by listing the application names, separated by the vertical bar character, for this reason often called the <a href="/facts/Pipeline_(Unix)/EIhovuT2">pipeline</a> character. A well-known example is the use of a <a href="/facts/Pagination/Xy6LKzJ2">pagination</a> application, such as <a href="/facts/More_(command)/emnMr8xz">more</a>, providing the user control over the display of the output stream on the display.
</p>
<h2 id="background">Background</h2>
<p>In most operating systems predating <a href="/facts/Unix/0pNL2seI">Unix</a>, programs had to explicitly connect to the appropriate input and output devices. OS-specific intricacies caused this to be a tedious programming task. On many systems it was necessary to obtain control of environment settings, access a local file table, determine the intended data set, and handle hardware correctly in the case of a <a href="/facts/Punch_card_reader/fP8jcPsT">punch card reader</a>, <a href="/facts/Magnetic_tape_drive/wj6IDTR1">magnetic tape drive</a>, <a href="/facts/Disk_drive/hnsXRb5X">disk drive</a>, <a href="/facts/Line_printer/QyWwtNBJ">line printer</a>, card punch, or interactive terminal.
</p><p>One of Unix's several groundbreaking advances was <i>abstract devices</i>, which removed the need for a program to know or care what kind of devices it was communicating with. Older operating systems forced upon the programmer a record structure and frequently <a href="/facts/Orthogonal/JVIjYPog">non-orthogonal</a> data semantics and device control.  Unix eliminated this complexity with the concept of a data stream:  an ordered sequence of data bytes which can be read until the <a href="/facts/End-of-file/VVBQjjN0">end of file</a>.  A program may also write bytes as desired and need not, and cannot easily declare their count or grouping.
</p><p>Another Unix breakthrough was to automatically associate input and output to terminal keyboard and terminal display, respectively, by default — the program (and programmer) did absolutely nothing to establish input and output for a typical input-process-output program (unless it chose a different paradigm).  In contrast, previous operating systems usually required some—often complex—<a href="/facts/Job_Control_Language/UCpfhoe4">job control language</a> to establish connections, or the equivalent burden had to be orchestrated by the program.
</p><p>Since Unix provided standard streams, the Unix <a href="/facts/C_(programming_language)/Ky2No763">C</a> runtime environment was obliged to support it as well.  As a result, most C runtime environments (and <a href="/facts/C_(programming_language)/Ky2No763">C's descendants</a>), regardless of the operating system, provide equivalent functionality.
</p>
<h2 id="standard-input-stdin">Standard input (stdin)</h2>
<p>Standard input is a stream from which a program reads its input data. The program requests data transfers by use of the <i>read</i> operation. Not all programs require stream input. For example, the <i><a href="/facts/Dir_(command)/oosA54R0">dir</a></i> and <i><a href="/facts/Ls/5GsH3v2a">ls</a></i> programs (which display file names contained in a directory) may take <a href="/facts/Command-line_interface/R9JpGmXQ">command-line arguments</a>, but perform their operations without any stream data input.
</p><p>Unless <a href="/facts/Redirection_(computing)/0qhx445L">redirected</a>, standard input is inherited from the parent process.  In the case of an interactive shell, that is usually associated with the input device of a <a href="/facts/Computer_terminal/fSlx05qV">terminal</a> (or <a href="/facts/Pseudoterminal/CV9rjfhz">pseudo terminal</a>) which is ultimately linked to a user's <a href="/facts/Keyboard_(computing)/MczF9LIS">keyboard</a>.
</p><p>On <a href="/facts/POSIX/mQkSt234">POSIX</a> systems, the <a href="/facts/File_descriptor/Iw74UKqG">file descriptor</a> for standard input is 0 (zero); the <a href="/facts/POSIX/mQkSt234">POSIX</a> <unistd.h> definition is STDIN_FILENO; the corresponding C <stdio.h> abstraction is provided via the FILE* stdin global variable. Similarly, the global C++  std::cin variable of type <iostream> provides an abstraction via <a href="/facts/Input%2foutput_(C%252B%252B)/I0GIssHr">C++ streams</a>. Similar abstractions exist in the standard I/O libraries of practically every <a href="/facts/Programming_language/cWTYbgWa">programming language</a>.
</p>
<h2 id="standard-output-stdout">Standard output (stdout)</h2>
<p>Standard output is a stream to which a program writes its output data.  The program requests data transfer with the <i>write</i> operation.  Not all programs generate output.  For example, the <i><a href="/facts/Rename_(computing)/0FHwfKp2">file rename</a></i> command (variously called <i><a href="/facts/Mv_(Unix)/BScugd1B">mv</a></i>, <i><a href="/facts/Move_(command)/uh2QlAf2">move</a></i>, or <i><a href="/facts/Ren_(command)/qMNSpKv8">ren</a></i>) is silent on success.
</p><p>Unless <a href="/facts/Redirection_(computing)/0qhx445L">redirected</a>, standard output is inherited from the parent process.  In the case of an interactive shell, that is usually the <a href="/facts/Text_terminal/fSlx05qV">text terminal</a> which initiated the program.
</p><p>The <a href="/facts/File_descriptor/Iw74UKqG">file descriptor</a> for standard output is 1 (one); the <a href="/facts/POSIX/mQkSt234">POSIX</a> <unistd.h> definition is STDOUT_FILENO; the corresponding C <stdio.h> variable is FILE* stdout; similarly, the C++ <iostream> variable is std::cout.
</p>
<h2 id="standard-error-stderr">Standard error (stderr)</h2>
<p>Standard error is another output stream typically used by programs to output <a href="/facts/Error_message/ko8elN1w">error messages</a> or diagnostics.  It is a stream independent of standard output and can be redirected separately.
</p><p>This solves the <a href="/facts/Semipredicate_problem/s5kH1GRQ">semi-predicate problem</a>, allowing output and errors to be distinguished, and is analogous to a function returning a pair of values – see <a href="/facts/Semipredicate_problem/s5kH1GRQ">Semipredicate problem § Multivalued return</a>. The usual destination is the <a href="/facts/Text_terminal/fSlx05qV">text terminal</a> which started the program to provide the best chance of being seen even if <i>standard output</i> is redirected (so not readily observed). For example, output of a program in a <a href="/facts/Pipeline_(Unix)/EIhovuT2">pipeline</a> is redirected to input of the next program or a text file, but errors from each program still go directly to the text terminal so they can be reviewed by the user in real time.
</p><p>It is acceptable and normal to direct <i>standard output</i> and <i>standard error</i> to the same destination, such as the text terminal.  Messages appear in the same order as the program writes them, unless <a href="/facts/Data_buffer/tVy4j2Dc">buffering</a> is involved. For example, in common situations the standard error stream is unbuffered but the standard output stream is line-buffered; in this case, text written to standard error later may appear on the terminal earlier, if the standard output stream buffer is not yet full.
</p><p>The <a href="/facts/File_descriptor/Iw74UKqG">file descriptor</a> for standard error is defined by <a href="/facts/POSIX/mQkSt234">POSIX</a> as 2 (two); the <i><unistd.h></i> header file provides the symbol STDERR_FILENO;<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> the corresponding C <stdio.h> variable is FILE* stderr. The C++ <iostream> standard header provides two variables associated with this stream: std::cerr and std::clog, the former being unbuffered and the latter using the same buffering mechanism as all other C++ streams.
</p><p><a href="/facts/Bourne_shell/wUCh3Qkl">Bourne</a>-style shells allow <i>standard error</i> to be redirected to the same destination that standard output is directed to using
</p>
 2>&1

<p><a href="/facts/C_shell/8XRuIg0K">csh</a>-style shells allow <i>standard error</i> to be redirected to the same destination that standard output is directed to using
</p>
 >&

<p>Standard error was added to Unix in the 1970s after several wasted phototypesetting runs ended with error messages being typeset instead of displayed on the user's terminal.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a>
</p>
<h2 id="timeline">Timeline</h2>
<h3>1950s: Fortran</h3>
<p><a href="/facts/Fortran/m1KqjcMU">Fortran</a> has the equivalent of Unix file descriptors: By convention, many Fortran implementations use unit numbers UNIT=5 for stdin, UNIT=6 for stdout and UNIT=0 for stderr.  In Fortran-2003, the intrinsic ISO_FORTRAN_ENV module was standardized to include the named constants INPUT_UNIT, OUTPUT_UNIT, and ERROR_UNIT to portably specify the unit numbers.
</p>
! FORTRAN 77 example
      PROGRAM MAIN
        INTEGER NUMBER
        READ(UNIT=5,*) NUMBER
        WRITE(UNIT=6,'(A,I3)') ' NUMBER IS: ',NUMBER
      END

! Fortran 2003 example
program main
  use iso_fortran_env
  implicit none
  integer :: number
  read (unit=INPUT_UNIT,*) number
  write (unit=OUTPUT_UNIT,'(a,i3)') 'Number is: ', number
end program

<h3>1960: ALGOL 60</h3>
<p><a href="/facts/ALGOL_60/QnpxUYQm">ALGOL 60</a> was criticized for having no standard file access.
</p>
<h3>1968: ALGOL 68</h3>
<p><a href="/facts/ALGOL_68/NTnc9fy7">ALGOL 68</a>'s input and output facilities were collectively referred to as the transput.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> <a href="/facts/Cornelis_H._A._Koster/kIfW8A49">Koster</a>  coordinated the definition of the <i>transput</i> standard.  The model included three standard channels: stand in, stand out, and stand back.
</p>
Example<table><tbody><tr><td colspan="2"># ALGOL 68 example #main:(  REAL number;  getf(stand in,($g$,number));  printf(($"Number is: "g(6,4)"OR "$,number)); # OR #  putf(stand out,($" Number is: "g(6,4)"!"$,number));  newline(stand out))</td></tr><tr><th>Input:</th><th>Output:</th></tr><tr><td>3.14159</td><td>Number is: +3.142 OR Number is: +3.142!</td></tr></tbody></table>
<h3>1970s: C and Unix</h3>
<p>In the <a href="/facts/C_programming_language/Ky2No763">C programming language</a>, the standard input, output, and error streams are attached to the existing Unix file descriptors 0, 1 and 2 respectively.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> In a <a href="/facts/POSIX/mQkSt234">POSIX</a> environment the <i><<a href="/facts/Unistd.h/3LMu4pne">unistd.h</a>></i> definitions <i>STDIN_FILENO</i>, <i>STDOUT_FILENO</i> or <i>STDERR_FILENO</i> should be used instead rather than <a href="/facts/Magic_number_(programming)/Xg7mVI7V">magic numbers</a>.   File pointers <i>stdin</i>, <i>stdout</i>, and <i>stderr</i> are also provided.
</p><p><a href="/facts/Ken_Thompson/KQtrw9YM">Ken Thompson</a> (designer and implementer of the original Unix operating system) modified <a href="/facts/Sort_(Unix)/oa9wxsq2">sort</a> in <a href="/facts/Version_5_Unix/5oWmUdwo">Version 5 Unix</a> to accept "-" as representing standard input, which spread to other utilities and became a part of the operating system as a <a href="/facts/Special_file/t8ISnXft">special file</a> in <a href="/facts/Version_8_Unix/5oWmUdwo">Version 8</a>. Diagnostics were part of standard output through <a href="/facts/Version_6_Unix/ev0YCVb4">Version 6</a>, after which <a href="/facts/Dennis_M._Ritchie/I1yu1UWU">Dennis M. Ritchie</a> created the concept of standard error.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a>
</p>
<h3>1995: Java</h3>
<p>In <a href="/facts/Java_(programming_language)/9ScgFyAL">Java</a>, the standard streams are referred to by <a href="https://docs.oracle.com/en/java/javase/19/docs/api/java.base/java/lang/System.html#in">System.in</a> (for stdin), <a href="https://docs.oracle.com/en/java/javase/19/docs/api/java.base/java/lang/System.html#out">System.out</a> (for stdout), and  <a href="https://docs.oracle.com/en/java/javase/19/docs/api/java.base/java/lang/System.html#err">System.err</a> (for stderr).<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> 
</p>
public static void main(String args[]) {
    try {
        BufferedReader br = 
          new BufferedReader(new InputStreamReader(System.in));
        String s = br.readLine();
        double number = Double.parseDouble(s);
        System.out.println("Number is:" + number);
    } catch (Exception e) {
        System.err.println("Error:" + e.getMessage());
    }
}

<h3>2000s: .NET</h3>
<p>In <a href="/facts/C_Sharp_(programming_language)/UC2gxeyb">C#</a> and other <a href="/facts/.NET_Framework/J6QDAUhP">.NET</a> languages, the standard streams are referred to by System.Console.In (for stdin), System.Console.Out (for stdout) and System.Console.Error (for stderr).<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> Basic read and write capabilities for the stdin and stdout streams are also accessible directly through the class System.Console (e.g. System.Console.WriteLine() can be used instead of System.Console.Out.WriteLine()).
</p><p>System.Console.In, System.Console.Out and System.Console.Error are System.IO.TextReader (stdin) and System.IO.TextWriter (stdout, stderr) objects, which only allow access to the underlying standard streams on a text basis. Full binary access to the standard streams must be performed through the System.IO.Stream objects returned by System.Console.OpenStandardInput(), System.Console.OpenStandardOutput() and System.Console.OpenStandardError() respectively.
</p>
// C# example
public static int Main(string[] args)
{
    try {
        string s = System.Console.In.ReadLine();
        double number = double.Parse(s);
        System.Console.Out.WriteLine("Number is: {0:F3}", number);
        return 0;

// If Parse() threw an exception
    } catch (ArgumentNullException) { 
        System.Console.Error.WriteLine("No number was entered!");
    } catch (FormatException) {
        System.Console.Error.WriteLine("The specified value is not a valid number!");
    } catch (OverflowException) {
        System.Console.Error.WriteLine("The specified number is too big!");
    }

return -1;
}

' Visual Basic .NET example

Public Function Main() As Integer
    Try
        Dim s As String = System.Console.[In].ReadLine()
        Dim number As Double = Double.Parse(s)
        System.Console.Out.WriteLine("Number is: {0:F3}", number)
        Return 0

' If Parse() threw an exception
    Catch ex As System.ArgumentNullException
        System.Console.[Error].WriteLine("No number was entered!")
    Catch ex2 As System.FormatException
        System.Console.[Error].WriteLine("The specified value is not a valid number!")
    Catch ex3 As System.OverflowException
        System.Console.[Error].WriteLine("The specified number is too big!")
    End Try

Return -1
End Function

<p>When applying the System.Diagnostics.Process <a href="/facts/Class_(computer_science)/zvzkSAtE">class</a> one can use the instance <a href="/facts/Property_(programming)/MRIIAw5g">properties</a> StandardInput, StandardOutput, and StandardError of that class to access the standard streams of the process.
</p>
<h3>2000 - : Python (2 or 3)</h3>
<p>The following example, written in <a href="/facts/Python_(programming_language)/YbuGqofa">Python</a>, shows how to redirect the standard input both to the standard output
and to a text file.
</p>
#!/usr/bin/env python
import sys
# Save the current stdout so that we can revert sys.stdout
# after we complete our redirection
stdin_fileno = sys.stdin
stdout_fileno = sys.stdout
# Redirect sys.stdout to the file
sys.stdout = open("myfile.txt", "w")
ctr = 0
for inps in stdin_fileno:
    ctrs = str(ctr)
    # Prints to the redirected stdout ()
    sys.stdout.write(ctrs + ") this is to the redirected --->" + inps + "\n")
    # Prints to the actual saved stdout handler
    stdout_fileno.write(ctrs + ") this is to the actual  --->" + inps + "\n")
    ctr = ctr + 1
# Close the file
sys.stdout.close()
# Restore sys.stdout to our old saved file handler
sys.stdout = stdout_fileno

<h3>GUIs</h3>
<p><a href="/facts/Graphical_user_interface/wBlQFWDP">Graphical user interfaces</a> (GUIs) do not always make use of the standard streams; they do when GUIs are wrappers of underlying scripts and/or console programs, for instance the <a href="/facts/Synaptic_(software)/3QdFfJxw">Synaptic</a> package manager GUI, which wraps apt commands in Debian and/or Ubuntu. GUIs created with scripting tools like Zenity and KDialog by <a href="/facts/KDE/PCh32IWA">KDE</a> project<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> make use of stdin, stdout, and stderr, and are based on simple scripts rather than a complete GUI programmed and compiled in C/C++ using <a href="/facts/Qt_(software)/gVhwlQnJ">Qt</a>, <a href="/facts/GTK/oLpVm9pp">GTK</a>, or other equivalent proprietary widget framework.
</p><p>The <a href="/facts/Services_menu/8jUKS0mA">Services menu</a>, as implemented on <a href="/facts/NeXTSTEP/eL0bymga">NeXTSTEP</a> and <a href="/facts/Mac_OS_X/Y93vVpTm">Mac OS X</a>, is also analogous to standard streams. On these operating systems, graphical applications can provide functionality through a system-wide menu that operates on the current selection in the GUI, no matter in what application.
</p><p>Some GUI programs, primarily on Unix, still write debug information to standard error. Others (such as many Unix media players) may read files from standard input. Popular Windows programs that open a separate console window in addition to their GUI windows are the emulators pSX and <a href="/facts/DOSBox/Du2egHYo">DOSBox</a>.
</p><p><a href="/facts/GTK-server/AD4rlUzR">GTK-server</a> can use stdin as a communication interface with an interpreted program to realize a GUI.
</p><p>The <a href="/facts/CLIM/kpj4eF6h">Common Lisp Interface Manager</a> paradigm "presents" GUI elements sent to an extended output stream.
</p>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Redirection_(computing)/0qhx445L">Redirection (computing)</a></li>
<li><a href="/facts/Stream_(computing)/2jtBAp0U">Stream (computing)</a></li>
<li><a href="/facts/Input%2foutput/WQTE8Jas">Input/output</a></li>
<li><a href="/facts/C_file_input%2foutput/m5n82Fqz">C file input/output</a></li>
<li><a href="/facts/SYSIN/d0kWFFAf">SYSIN</a> and <a href="/facts/SYSOUT/d0kWFFAf">SYSOUT</a></li>
<li><a href="/facts/Files-11/oXRKHxRE">Standard streams in the Files-11 file system</a></li></ul>

<h2 id="sources">Sources</h2>

<ul><li>"<a href="https://www.gnu.org/software/libc/manual/html_node/Standard-Streams.html">Standard Streams</a>", <a href="https://www.gnu.org/software/libc/manual/html_node/index.html">The GNU C Library</a></li>
<li><i>KRONOS 2.1 Reference Manual</i>, Control Data Corporation, Part Number 60407000, 1974</li>
<li><i>NOS Version 1 Applications Programmer's Instant</i>, Control Data Corporation, Part Number 60436000, 1978</li>
<li><a href="http://www.bitsavers.org/pdf/honeywell/multics/AG90-03_PgmgIntro_Dec81.pdf">Level 68 Introduction to Programming on MULTICS</a> <a href="https://web.archive.org/web/20210225022744/http://www.bitsavers.org/pdf/honeywell/multics/AG90-03_PgmgIntro_Dec81.pdf">Archived</a> 2021-02-25 at the <a href="/facts/Wayback_Machine/nmQ3a6JC">Wayback Machine</a>, Honeywell Corporation, 1981</li>
<li><a href="https://web.archive.org/web/20191009002342/https://pdfs.semanticscholar.org/a8e4/4d068a376c42513a4e10d6a751702710afee.pdf">Evolution of the MVS Operating System</a>, IBM Corporation, 1981</li>
<li><i>Lions' Commentary on UNIX Sixth Edition</i>, John Lions, <a href="/facts/ISBN_(identifier)/15AdSPa9">ISBN</a> 1-57398-013-7, 1977</li>
<li><a href="http://msdn2.microsoft.com/en-us/library/system.console.aspx">Console Class, .NET Framework Class Library</a>, Microsoft Corporation, 2008</li></ul>

<h2 id="external-links">External links</h2>
<ul><li><a href="http://www.linfo.org/standard_input.html">Standard Input Definition</a> - by The Linux Information Project</li>
<li><a href="http://www.linfo.org/standard_output.html">Standard Output Definition</a> - by The Linux Information Project</li>
<li><a href="http://www.linfo.org/standard_error.html">Standard Error Definition</a> - by The Linux Information Project</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>D. M. Ritchie, "A Stream Input-Output System", AT&T Bell Laboratories Technical Journal, 68(8), October 1984. <a href="https://cseweb.ucsd.edu/classes/fa01/cse221/papers/ritchie-stream-io-belllabs84.pdf" target="_blank">https://cseweb.ucsd.edu/classes/fa01/cse221/papers/ritchie-stream-io-belllabs84.pdf</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>"<unistd.h>". The Open Group Base Specifications Issue 6—IEEE Std 1003.1, 2004 Edition. The Open Group. 2004. <a href="http://pubs.opengroup.org/onlinepubs/009695399/basedefs/unistd.h.html" target="_blank">http://pubs.opengroup.org/onlinepubs/009695399/basedefs/unistd.h.html</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Johnson, Steve (2013-12-11). "[TUHS] Graphic Systems C/A/T phototypesetter" (Mailing list). Archived from the original on 2020-09-25. Retrieved 2020-11-07. <a href="/wiki/Stephen_C._Johnson" target="_blank">/wiki/Stephen_C._Johnson</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>"Revised Report on the Algorithmic Language Algol 68", edited by A. van Wijngaarden, B.J. Mailloux, J.E.L. Peck, C.H.A. Koster, M. Sintzoff, C.H. Lindsey, L.G.L.T. Meertens and R.G. Fisker, Section 10.3. <a href="http://www.softwarepreservation.org/projects/ALGOL/report/Algol68_revised_report-AB.pdf" target="_blank">http://www.softwarepreservation.org/projects/ALGOL/report/Algol68_revised_report-AB.pdf</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>"Stdin(3): Standard I/O streams - Linux man page". die.net. Archived from the original on Jun 8, 2023. <a href="http://linux.die.net/man/3/stdin" target="_blank">http://linux.die.net/man/3/stdin</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
<li id="fn:6"><p>McIlroy, M. D. (1987). A Research Unix reader: annotated excerpts from the Programmer's Manual, 1971–1986 (PDF) (Technical report). CSTR. Bell Labs. 139. Archived (PDF) from the original on Dec 15, 2023. <a href="/wiki/Doug_McIlroy" target="_blank">/wiki/Doug_McIlroy</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li>
<li id="fn:7"><p>"System (Java Platform SE 7)". Oracle Help Center. Retrieved 20 July 2012. <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/System.html" target="_blank">http://docs.oracle.com/javase/7/docs/api/java/lang/System.html</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li>
<li id="fn:8"><p>".NET Framework 4.7.1, mscorlib, console.cs". Reference Source - Microsoft. Archived from the original on Dec 10, 2017. Retrieved 2017-12-10. <a href="https://referencesource.microsoft.com/#mscorlib/system/console.cs,34" target="_blank">https://referencesource.microsoft.com/#mscorlib/system/console.cs,34</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li>
<li id="fn:9"><p>Kißling, Kristian (2009). "Adding graphic elements to your scripts with Zenity and KDialog". Linux Magazine. Retrieved 2021-04-11. <a href="https://www.linux-magazine.com/Issues/2009/99/Zenity-and-KDialog" target="_blank">https://www.linux-magazine.com/Issues/2009/99/Zenity-and-KDialog</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li>
</ol>

Standard streams open-in-new

Standard streams