blocks|key|1491976|text|Perl：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1491977|$output+=+`foo`;|code-block|syntax|javascript|1491978|补充说:这真的是一个多方面的平局。上面的代码也是有效的PHP，例如，Ruby也使用相同的反引号表示法。|1491979|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Perl:

<pre><code>$output = `foo`;
</code></pre>

ADDED: This is really a multi-way tie. The above is also valid PHP, and Ruby, for example, uses the same backtick notation as well.

blocks|key|1492374|text|Python|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492375|from+subprocess+import+check_output+as+qx

output+=+qx(['ls',+'-lt'])|code-block|syntax|javascript|1492376|Python+<2.7或<3.1|offset|length|1492377|从subprocess.py中提取subprocess.check_output()或改编类似以下内容：|style|CODE|1492378|import+subprocess

def+cmd_output(args,+**kwds):
++kwds.setdefault("stdout",+subprocess.PIPE)
++kwds.setdefault("stderr",+subprocess.STDOUT)
++p+=+subprocess.Popen(args,+**kwds)
++return+p.communicate()[0]

print+cmd_output("ls+-lt".split())|1492379|subprocess模块从2.4开始就已经包含在stdlib中。|1492380|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.python.org/dev/library/subprocess.html#subprocess.check_output|1|http://docs.python.org/py3k/library/subprocess.html#subprocess.check_output|2|http://svn.python.org/view/python/trunk/Lib/subprocess.py?view=markup|3|http://docs.python.org/library/subprocess.html^0|0|0|8|3|0|D|3|1|0|H|P|1|D|2|0|0|0|A|3|0^^$0|@$1|2|3|4|5|6|7|16|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|17|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|18|8|@]|9|@$I|19|J|1A|1|1B]|$I|1C|J|1D|1|1E]]|A|$]]|$1|K|3|L|5|6|7|1F|8|@$I|1G|J|1H|M|N]]|9|@$I|1I|J|1J|1|1K]]|A|$]]|$1|O|3|P|5|D|7|1L|8|@]|9|@]|A|$E|F]]|$1|Q|3|R|5|6|7|1M|8|@]|9|@$I|1N|J|1O|1|1P]]|A|$]]|$1|S|3|-4|5|6|7|1Q|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z]]|10|$5|V|W|X|A|$Y|11]]|12|$5|V|W|X|A|$Y|13]]|14|$5|V|W|X|A|$Y|15]]]]

<h2>Python</h2>

<pre><code>from subprocess import check_output as qx

output = qx(['ls', '-lt'])
</code></pre>

<h3>Python &lt;<a href="http://docs.python.org/dev/library/subprocess.html#subprocess.check_output" rel="noreferrer">2.7</a> or &lt;<a href="http://docs.python.org/py3k/library/subprocess.html#subprocess.check_output" rel="noreferrer">3.1</a></h3>

Extract <code>subprocess.check_output()</code> from <a href="http://svn.python.org/view/python/trunk/Lib/subprocess.py?view=markup" rel="noreferrer">subprocess.py</a> or adapt something similar to:

<pre><code>import subprocess

def cmd_output(args, **kwds):
 kwds.setdefault("stdout", subprocess.PIPE)
 kwds.setdefault("stderr", subprocess.STDOUT)
 p = subprocess.Popen(args, **kwds)
 return p.communicate()[0]

print cmd_output("ls -lt".split())
</code></pre>

The <a href="http://docs.python.org/library/subprocess.html" rel="noreferrer">subprocess</a> module has been in the stdlib since 2.4.

blocks|key|1707077|text|Python：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1707078|import+os
output+=+os.popen("foo").read()|code-block|syntax|javascript|1707079|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Python:

<pre><code>import os
output = os.popen("foo").read()
</code></pre>

blocks|key|1492345|text|在Perl中还有另一种方法(TIMTOWTDI)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492346|$output+=+<<`END`;
ls
END|code-block|syntax|javascript|1492347|当在Perl程序中嵌入相对较大的shell脚本时，这特别有用|1492348|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Yet another way to do it in Perl (TIMTOWTDI)

<pre><code>$output = &lt;&lt;`END`;
ls
END
</code></pre>

This is specially useful when embedding a relatively large shell script in a Perl program

blocks|key|1492174|text|Ruby:反引号或'%25x‘内置语法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492175|puts+`ls`;
puts+%25x{ls};|code-block|syntax|javascript|1492176|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Ruby: either backticks or the '%x' builtin syntax.

<pre><code>puts `ls`;
puts %x{ls};
</code></pre>

blocks|key|1492268|text|perl中的另一种方法|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492269|$output+=+qx/ls/;|code-block|syntax|javascript|1492270|这样做的好处是你可以选择自己的分隔符，这样就可以在命令中使用`(不过如果你真的需要的话，我想你应该重新考虑一下你的设计)。另一个重要的优点是，如果你使用单引号作为分隔符，变量将不会被插入(一个非常有用的)|1492271|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

An alternative method in perl

<pre><code>$output = qx/ls/;
</code></pre>

This had the advantage that you can choose your delimiters, making it possible to use ` in the command (though IMHO you should reconsider your design if you really need to do that). Another important advantage is that if you use single quotes as delimiter, variables will not be interpolated (a very useful)

blocks|key|1492537|text|Haskell：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492538|import+Control.Exception
import+System.IO
import+System.Process
main+=+bracket+(runInteractiveCommand+"ls")+close+$+\(_,+hOut,+_,+_)+->+do
++++output+<-+hGetContents+hOut
++++putStr+output
++where+close+(hIn,+hOut,+hErr,+pid)+=
++++++++++mapM_+hClose+[hIn,+hOut,+hErr]+>>+waitForProcess+pid|code-block|syntax|javascript|1492539|安装了MissingH后：|offset|length|1492540|import+System.Cmd.Utils
main+=+do
++++(pid,+output)+<-+pipeFrom+"ls"+[]
++++putStr+output
++++forceSuccess+pid|1492541|在Perl和Ruby等“粘合”语言中，这是一个简单的操作，但Haskell并非如此。|1492542|entityMap|0|LINK|mutability|MUTABLE|url|http://software.complete.org/software/projects/show/missingh^0|0|0|3|8|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@]|9|@$I|Z|J|10|1|11]]|A|$]]|$1|K|3|L|5|D|7|12|8|@]|9|@]|A|$E|F]]|$1|M|3|N|5|6|7|13|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

Haskell:

<pre><code>import Control.Exception
import System.IO
import System.Process
main = bracket (runInteractiveCommand "ls") close $ \(_, hOut, _, _) -&gt; do
 output &lt;- hGetContents hOut
 putStr output
 where close (hIn, hOut, hErr, pid) =
 mapM_ hClose [hIn, hOut, hErr] &gt;&gt; waitForProcess pid
</code></pre>

With <a href="http://software.complete.org/software/projects/show/missingh" rel="nofollow noreferrer">MissingH</a> installed:

<pre><code>import System.Cmd.Utils
main = do
 (pid, output) &lt;- pipeFrom "ls" []
 putStr output
 forceSuccess pid
</code></pre>

This is an easy operation in "glue" languages like Perl and Ruby, but Haskell isn't.

blocks|key|1492096|text|在shell中|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492097|OUTPUT=`ls`|code-block|syntax|javascript|1492098|或者另选地|1492099|OUTPUT=$(ls)|1492100|第二种方法更好，因为它允许嵌套，但与第一种方法不同，并不是所有的shell都支持它。|1492101|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

In shell

<pre><code>OUTPUT=`ls`
</code></pre>

or alternatively

<pre><code>OUTPUT=$(ls)
</code></pre>

This second method is better because it allows nesting, but isn't supported by all shells, unlike the first method.

blocks|key|1492296|text|Erlang：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492297|os:cmd("ls")|code-block|syntax|javascript|1492298|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Erlang:

<pre><code>os:cmd("ls")
</code></pre>

blocks|key|1492024|text|Mathematica：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492025|output+=+Import["!foo",+"Text"];|code-block|syntax|javascript|1492026|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Mathematica:

<pre><code>output = Import["!foo", "Text"];
</code></pre>

blocks|key|1492408|text|还有另一种方式(或2种！)在Perl中...|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492409|open+my+$pipe,+'ps+%7C';
my+@output+=+<+$pipe+>;
say+@output;|code-block|syntax|javascript|1492410|open也可以这样编写...|offset|length|1492411|open+my+$pipe,+'-%7C',+'ps'|1492412|entityMap|0|LINK|mutability|MUTABLE|url|http://perldoc.perl.org/functions/open.html^0|0|0|0|4|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@$I|X|J|Y|1|Z]]|A|$]]|$1|K|3|L|5|D|7|10|8|@]|9|@]|A|$E|F]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

Yet another way (or 2!) in Perl....

<pre><code>open my $pipe, 'ps |';
my @output = &lt; $pipe &gt;;
say @output;
</code></pre>

<a href="http://perldoc.perl.org/functions/open.html" rel="nofollow noreferrer">open</a> can also be written like so...

<pre><code>open my $pipe, '-|', 'ps'
</code></pre>

blocks|key|1707565|text|几年前，我为jEdit编写了一个接口到本机应用程序的plugin。这是我用来从正在运行的可执行文件中获取流的方法。唯一要做的就是while((String+s+=+stdout.readLine())!=null){...}|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1707566|/*+File:++++IOControl.java
+*
+*+created:+10+July+2003
+*+author:++dsm
+*/
package+org.jpop.io;

import+java.io.BufferedReader;
import+java.io.InputStreamReader;
import+java.io.PrintStream;

/**
+*++Controls+the+I/O+for+a+process.+When+using+the+std[in%7Cout%7Cerr]+streams,+they+must+all+be+put+on
+*++different+threads+to+avoid+blocking!
+*
+*+@author+++++dsm
+*+@version++++1.5
+*/
public+class+IOControl+extends+Object+{
++++private+Process+process;
++++private+BufferedReader+stdout;
++++private+BufferedReader+stderr;
++++private+PrintStream+stdin;

++++/**
+++++*++Constructor+for+the+IOControl+object
+++++*
+++++*+@param++process++The+process+to+control+I/O+for
+++++*/
++++public+IOControl(Process+process)+{
++++++++this.process+=+process;
++++++++this.stdin+=+new+PrintStream(process.getOutputStream());
++++++++this.stdout+=+new+BufferedReader(new+InputStreamReader(process.getInputStream()));
++++++++this.stderr+=+new+BufferedReader(new+InputStreamReader(process.getErrorStream()));
++++}

++++/**
+++++*++Gets+the+stdin+attribute+of+the+IOControl+object
+++++*
+++++*+@return++++The+stdin+value
+++++*/
++++public+PrintStream+getStdin()+{
++++++++return+this.stdin;
++++}

++++/**
+++++*++Gets+the+stdout+attribute+of+the+IOControl+object
+++++*
+++++*+@return++++The+stdout+value
+++++*/
++++public+BufferedReader+getStdout()+{
++++++++return+this.stdout;
++++}

++++/**
+++++*++Gets+the+stderr+attribute+of+the+IOControl+object
+++++*
+++++*+@return++++The+stderr+value
+++++*/
++++public+BufferedReader+getStderr()+{
++++++++return+this.stderr;
++++}

++++/**
+++++*++Gets+the+process+attribute+of+the+IOControl+object.+To+monitor+the+process+(as+opposed+to
+++++*++just+letting+it+run+by+itself)+its+necessary+to+create+a+thread+like+this:+<pre>
+++++*.+IOControl+ioc;
+++++*.
+++++*.+new+Thread(){
+++++*.+++++public+void+run(){
+++++*.+++++++++while(true){++++//+only+necessary+if+you+want+the+process+to+respawn
+++++*.+++++++++++++try{
+++++*.+++++++++++++++++ioc+=+new+IOControl(Runtime.getRuntime().exec("procname"));
+++++*.+++++++++++++++++//+add+some+code+to+handle+the+IO+streams
+++++*.+++++++++++++++++ioc.getProcess().waitFor();
+++++*.+++++++++++++}catch(InterruptedException+ie){
+++++*.+++++++++++++++++//+deal+with+exception
+++++*.+++++++++++++}catch(IOException+ioe){
+++++*.+++++++++++++++++//+deal+with+exception
+++++*.+++++++++++++}
+++++*.
+++++*.+++++++++++++//+a+break+condition+can+be+included+here+to+terminate+the+loop
+++++*.+++++++++}+++++++++++++++//+only+necessary+if+you+want+the+process+to+respawn
+++++*.+++++}
+++++*.+}.start();
+++++*++</pre>
+++++*
+++++*+@return++++The+process+value
+++++*/
++++public+Process+getProcess()+{
++++++++return+this.process;
++++}
}|code-block|syntax|javascript|1707567|entityMap|0|LINK|mutability|MUTABLE|url|http://jedit.org/|1|https://sourceforge.net/projects/jpop^0|1S|1C|6|5|0|Q|6|1|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@$9|X|A|Y|1|Z]|$9|10|A|11|1|12]]|E|$]]|$1|F|3|G|5|H|7|13|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|14|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]|S|$5|N|O|P|E|$Q|T]]]]

Years ago I wrote a <a href="https://sourceforge.net/projects/jpop" rel="nofollow noreferrer">plugin</a> for <a href="http://jedit.org" rel="nofollow noreferrer">jEdit</a> that interfaced to a native application. This is what I used to get the streams off the running executable. Only thing left to do is <code>while((String s = stdout.readLine())!=null){...}</code>:

<pre><code>/* File: IOControl.java
 *
 * created: 10 July 2003
 * author: dsm
 */
package org.jpop.io;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintStream;

/**
 * Controls the I/O for a process. When using the std[in|out|err] streams, they must all be put on
 * different threads to avoid blocking!
 *
 * @author dsm
 * @version 1.5
 */
public class IOControl extends Object {
 private Process process;
 private BufferedReader stdout;
 private BufferedReader stderr;
 private PrintStream stdin;

 /**
 * Constructor for the IOControl object
 *
 * @param process The process to control I/O for
 */
 public IOControl(Process process) {
 this.process = process;
 this.stdin = new PrintStream(process.getOutputStream());
 this.stdout = new BufferedReader(new InputStreamReader(process.getInputStream()));
 this.stderr = new BufferedReader(new InputStreamReader(process.getErrorStream()));
 }

 /**
 * Gets the stdin attribute of the IOControl object
 *
 * @return The stdin value
 */
 public PrintStream getStdin() {
 return this.stdin;
 }

 /**
 * Gets the stdout attribute of the IOControl object
 *
 * @return The stdout value
 */
 public BufferedReader getStdout() {
 return this.stdout;
 }

 /**
 * Gets the stderr attribute of the IOControl object
 *
 * @return The stderr value
 */
 public BufferedReader getStderr() {
 return this.stderr;
 }

 /**
 * Gets the process attribute of the IOControl object. To monitor the process (as opposed to
 * just letting it run by itself) its necessary to create a thread like this: &lt;pre&gt;
 *. IOControl ioc;
 *.
 *. new Thread(){
 *. public void run(){
 *. while(true){ // only necessary if you want the process to respawn
 *. try{
 *. ioc = new IOControl(Runtime.getRuntime().exec("procname"));
 *. // add some code to handle the IO streams
 *. ioc.getProcess().waitFor();
 *. }catch(InterruptedException ie){
 *. // deal with exception
 *. }catch(IOException ioe){
 *. // deal with exception
 *. }
 *.
 *. // a break condition can be included here to terminate the loop
 *. } // only necessary if you want the process to respawn
 *. }
 *. }.start();
 * &lt;/pre&gt;
 *
 * @return The process value
 */
 public Process getProcess() {
 return this.process;
 }
}
</code></pre>

blocks|key|1707591|text|别忘了Tcl：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1707592|set+result+[exec+ls]|code-block|syntax|javascript|1707593|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Don't forget Tcl:

<pre><code>set result [exec ls]
</code></pre>

blocks|key|1492810|text|C#+3.0，比this+one更少冗长|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1492811|using+System;
using+System.Diagnostics;

class+Program
{
++++static+void+Main()
++++{
++++++++var+info+=+new+ProcessStartInfo("cmd",+"/c+dir")+{+UseShellExecute+=+false,+RedirectStandardOutput+=+true+};
++++++++Console.WriteLine(Process.Start(info).StandardOutput.ReadToEnd());
++++}
}|code-block|syntax|javascript|1492812|注意:生产代码应该正确地处理进程对象...|1492813|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/236737/language-showdown-how-do-you-make-a-system-call-that-returns-the-stdout-output-a#388176^0|8|8|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|C|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

C# 3.0, less verbose than <a href="https://stackoverflow.com/questions/236737/language-showdown-how-do-you-make-a-system-call-that-returns-the-stdout-output-a#388176">this one</a>:

<pre><code>using System;
using System.Diagnostics;

class Program
{
 static void Main()
 {
 var info = new ProcessStartInfo("cmd", "/c dir") { UseShellExecute = false, RedirectStandardOutput = true };
 Console.WriteLine(Process.Start(info).StandardOutput.ReadToEnd());
 }
}
</code></pre>

Caveat: Production code should properly dispose the Process object...

blocks|key|1492187|text|在PHP中|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492188|$output+=+`ls`;|code-block|syntax|javascript|1492189|或|1492190|$output+=+shell_exec('ls');|1492191|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

In PHP

<pre><code>$output = `ls`;
</code></pre>

or

<pre><code>$output = shell_exec('ls');
</code></pre>

blocks|key|1707426|text|C(带glibc扩展)：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1707427|#define+_GNU_SOURCE
#include+<stdio.h>
int+main()+{
++++char+*s+=+NULL;
++++FILE+*p+=+popen("ls",+"r");
++++getdelim(&s,+NULL,+'\0',+p);
++++pclose(p);
++++printf("%25s",+s);
++++return+0;
}|code-block|syntax|javascript|1707428|好吧，不是很简洁或者干净利落。这就是C的生活。|1707429|entityMap^0|3|5|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|S|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

C (with <code>glibc</code> extension):

<pre><code>#define _GNU_SOURCE
#include &lt;stdio.h&gt;
int main() {
 char *s = NULL;
 FILE *p = popen("ls", "r");
 getdelim(&amp;s, NULL, '\0', p);
 pclose(p);
 printf("%s", s);
 return 0;
}
</code></pre>

Okay, not really concise or clean. That's life in C...

blocks|key|1707706|text|在符合Posix的系统上使用C：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1707707|#include+<stdio.h>+

FILE*+stream+=+popen("/path/to/program",+"rw");
fprintf(stream,+"foo\n");+/*+Use+like+you+would+a+file+stream.+*/
fclose(stream);|code-block|syntax|javascript|1707708|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

In C on Posix conformant systems:

<pre><code>#include &lt;stdio.h&gt; 

FILE* stream = popen("/path/to/program", "rw");
fprintf(stream, "foo\n"); /* Use like you would a file stream. */
fclose(stream);
</code></pre>

blocks|key|1707755|text|为什么这里仍然没有c#人员:)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1707756|这是如何在C#中做到这一点。内置的方式。|1707757|using+System;
using+System.Collections.Generic;
using+System.Linq;
using+System.Text;
using+System.Diagnostics;

namespace+TestConsole
{
++++class+Program
++++{
++++++++static+void+Main(string[]+args)
++++++++{
++++++++++++Process+p+=+new+Process();

++++++++++++p.StartInfo.UseShellExecute+=+false;
++++++++++++p.StartInfo.CreateNoWindow+=+true;
++++++++++++p.StartInfo.RedirectStandardOutput+=+true;
++++++++++++p.StartInfo.RedirectStandardError+=+true;
++++++++++++p.StartInfo.FileName+=+"cmd";
++++++++++++p.StartInfo.Arguments+=+"/c+dir";
++++++++++++p.Start();

++++++++++++string+res+=+p.StandardOutput.ReadToEnd();
++++++++++++Console.WriteLine(res);
++++++++}

++++}
}|code-block|syntax|javascript|1707758|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Why there is still no c# guy here :)

This is how to do it in C#. The built-in way.

<pre><code>using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;

namespace TestConsole
{
 class Program
 {
 static void Main(string[] args)
 {
 Process p = new Process();

 p.StartInfo.UseShellExecute = false;
 p.StartInfo.CreateNoWindow = true;
 p.StartInfo.RedirectStandardOutput = true;
 p.StartInfo.RedirectStandardError = true;
 p.StartInfo.FileName = "cmd";
 p.StartInfo.Arguments = "/c dir";
 p.Start();

 string res = p.StandardOutput.ReadToEnd();
 Console.WriteLine(res);
 }

 }
}
</code></pre>

blocks|key|1492909|text|下面是另一种Lisp方式：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492910|(defun+execute+(program+parameters+&optional+(buffer-size+1000))
++(let+((proc+(sb-ext:run-program+program+parameters+:search+t+:output+:stream))
++++++++(output+(make-array+buffer-size+:adjustable+t+:fill-pointer+t+
++++++++++++++++++++++++++++:element-type+'character)))
++++(with-open-stream+(stream+(sb-ext:process-output+proc))
++++++(setf+(fill-pointer+output)+(read-sequence+output+stream)))
++++output))|code-block|syntax|javascript|1492911|然后，获取字符串：|1492912|(execute+"cat"+'("/etc/hosts"))|1492913|如果你想运行一个命令来创建打印大量信息到STDOUT，你可以像这样运行它：|1492914|(execute+"big-writer"+'("some"+"parameters")+1000000)|1492915|最后一个参数为big-writer的输出预分配了大量空间。我猜这个函数可能比一次读取一行输出流更快。|1492916|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|W|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

Here's another Lisp way:

<pre><code>(defun execute (program parameters &amp;optional (buffer-size 1000))
 (let ((proc (sb-ext:run-program program parameters :search t :output :stream))
 (output (make-array buffer-size :adjustable t :fill-pointer t 
 :element-type 'character)))
 (with-open-stream (stream (sb-ext:process-output proc))
 (setf (fill-pointer output) (read-sequence output stream)))
 output))
</code></pre>

Then, to get your string:

<pre><code>(execute "cat" '("/etc/hosts"))
</code></pre>

If you want to run a command that creates prints a great deal of info to STDOUT, you can run it like this:

<pre><code>(execute "big-writer" '("some" "parameters") 1000000)
</code></pre>

The last parameter preallocates a large amount of space for the output from big-writer. I'm guessing this function could be faster than reading the output stream one line at a time.

blocks|key|1492940|text|Lua|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1492941|++++foo+=+io.popen("ls"):read("*a")|code-block|syntax|javascript|1492942|entityMap|0|LINK|mutability|MUTABLE|url|http://lua.org/^0|0|3|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

<a href="http://lua.org" rel="nofollow noreferrer">Lua</a>:

<pre><code> foo = io.popen("ls"):read("*a")
</code></pre>

blocks|key|1492479|text|J|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1492480|output=:2!:0'ls'|code-block|syntax|javascript|1492481|entityMap|0|LINK|mutability|MUTABLE|url|http://www.jsoftware.com/^0|0|1|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

<a href="http://www.jsoftware.com/" rel="nofollow noreferrer">J</a>:

<pre><code>output=:2!:0'ls'
</code></pre>

blocks|key|1707653|text|Perl，另一种方式：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1707654|use+IPC::Run3

my+($stdout,+$stderr);
run3+['ls'],+undef,+\$stdout,+\$stderr
++++or+die+"ls+failed";|code-block|syntax|javascript|1707655|这很有用，因为您可以提供命令输入，并分别返回stderr和stdout。远不及IPC::Run那样整洁/可怕/缓慢/令人不安，它可以设置子例程的管道。|offset|length|style|CODE|1707656|entityMap^0|0|0|13|8|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Perl, another way:

<pre><code>use IPC::Run3

my ($stdout, $stderr);
run3 ['ls'], undef, \$stdout, \$stderr
 or die "ls failed";
</code></pre>

Useful because you can feed the command input, and get back both stderr and stdout separately. Nowhere near as neat/scary/slow/disturbing as <code>IPC::Run</code>, which can set up pipes to subroutines.

blocks|key|1707802|text|图标/取消图标：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1707803|stream+:=+open("ls",+"p")
while+line+:=+read(stream)+do+{+
++++#+stuff
}|code-block|syntax|javascript|1707804|文档称其为管道。其中一个好处是，它使输出看起来像是在读取文件。这也意味着，如果需要，您可以写入应用程序的stdin。|1707805|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

<h3>Icon/Unicon:</h3>

<pre><code>stream := open("ls", "p")
while line := read(stream) do { 
 # stuff
}
</code></pre>

The docs call this a pipe. One of the good things is that it makes the output look like you're just reading a file. It also means you can write to the app's stdin, if you must.

blocks|key|1707997|text|Clozure+Common+Lisp：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1707998|(with-output-to-string+(stream)
+++(run-program+"ls"+'("-l")+:output+stream))|code-block|syntax|javascript|1707999|LispWorks|1708000|(with-output-to-string+(*standard-output*)
++(sys:call-system-showing-output+"ls+-l"+:prefix+""+:show-cmd+nil))|1708001|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Clozure Common Lisp:

<pre><code>(with-output-to-string (stream)
 (run-program "ls" '("-l") :output stream))
</code></pre>

LispWorks

<pre><code>(with-output-to-string (*standard-output*)
 (sys:call-system-showing-output "ls -l" :prefix "" :show-cmd nil))
</code></pre>

Perl and PHP do this with backticks. For example,

<pre><code>$output = `ls`;
</code></pre>

Returns a directory listing. A similar function, <code>system("foo")</code>, returns the operating system return code for the given command foo. I'm talking about a variant that returns whatever foo prints to stdout.

How do other languages do this? Is there a canonical name for this function? (I'm going with "backtick"; though maybe I could coin "syslurp".)

Making a system call that returns the stdout output as a string

Python

Erlang

Perl

Perl和PHP用反引号来做这件事。例如,$output = `ls`;返回目录列表。类似的函数system("foo")返回给定命令foo的操作系统返回码。我说的是一个变量，它将foo打印的内容返回给stdout。其他语言是如何做到这一点的？这个函数有没有一个规范的名字？(我使用"backtick"；不过也许我可以造出“syslurp”。)

问进行系统调用，将stdout输出作为字符串返回
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