24 种语言执行外部命令的方法
在这个例子中展示用不同语言调用外部命令的方法。觉得这个挺有意思，转来给大家看看，也许某一天你会觉得有用。
这些语言包括
Ada
AppleScript
C
C++
C#
E
Forth
Haskell
IDL
J
Java
Logo
MAXScript
Objective-C
OCaml
Perl
PHP
Pop11
Python
Raven
Ruby
Tcl
Toka
UNIX Shell
原文在 http://www.rosettacode.org/wiki/Execute_a_System_Command
Ada
with Interfaces.C; use Interfaces.C; procedure Execute_System is function Sys (Arg : Char_Array) return Integer; pragma Import(C, Sys, "system"); Ret_Val : Integer; begin Ret_Val := Sys(To_C("ls")); end Execute_System; AppleScript
do shell script "ls" without altering line endings
C
支持版本 gcc version 4.0.1
平台: BSD
#include <stdlib.h> int main() { system("ls"); } C++
支持版本: Visual C++ version 2005
system("pause"); C#
支持版本: MCS version 1.2.3.1
using System; class Execute { static void Main() { System.Diagnostics.Process proc = new System.Diagnostics.Process(); proc.EnableRaisingEvents=false; proc.StartInfo.FileName="ls"; proc.Start(); } } E
def ls := makeCommand("ls") ls("-l") def [results, _, _] := ls.exec(["-l"]) when (results) -> { def [exitCode, out, err] := results print(out) } catch problem { print(`failed to execute ls: $problem`) } Forth
支持版本: gforth version 0.6.2
s" ls" system
Haskell
支持版本: GHCi version 6.6
import System.Cmd main = system "ls"
IDL
带屏幕输出的 "ls" ：
$ls
将输出保存到数组"result"：
spawn,"ls",result
异步执行，将输出转到LUN "unit"，以便在以后读取：
spawn,"ls",unit=unit
J
J语言系统命令界面由标准的"task"脚本提供：
load’task’
NB. Execute a command and wait for it to complete
shell ‘dir’
NB. Execute a command but don’t wait for it to complete
fork ‘notepad’
NB. Execute a command and capture its stdout
stdout =: shell ‘dir’
NB. Execute a command, provide it with stdin,
NB. and capture its stdout
stdin =: ‘blahblahblah’
stdout =: stdin spawn ‘grep blah’
Java
支持版本: Java version 1.4+
有两种执行系统命令的方法，简单的方法会挂起JVM
import java.io.IOException; import java.io.InputStream; public class MainEntry { public static void main(String[] args) { executeCmd("ls -oa"); } private static void executeCmd(String string) { InputStream pipedOut = null; try { Process aProcess = Runtime.getRuntime().exec(string); aProcess.waitFor(); pipedOut = aProcess.getInputStream(); byte buffer[] = new byte[2048]; int read = pipedOut.read(buffer); // Replace following code with your intends processing tools while(read >= 0) { System.out.write(buffer, 0, read); read = pipedOut.read(buffer); } } catch (IOException e) { e.printStackTrace(); } catch (InterruptedException ie) { ie.printStackTrace(); } finally { if(pipedOut != null) { try { pipedOut.close(); } catch (IOException e) { } } } } } 正确的方法使用进程提供的线程去读取InputStream。
import java.io.IOException; import java.io.InputStream; public class MainEntry { public static void main(String[] args) { // the command to execute executeCmd("ls -oa"); } private static void executeCmd(String string) { InputStream pipedOut = null; try { Process aProcess = Runtime.getRuntime().exec(string); // These two thread shall stop by themself when the process end Thread pipeThread = new Thread(new StreamGobber(aProcess.getInputStream())); Thread errorThread = new Thread(new StreamGobber(aProcess.getErrorStream())); pipeThread.start(); errorThread.start(); aProcess.waitFor(); } catch (IOException e) { e.printStackTrace(); } catch (InterruptedException ie) { ie.printStackTrace(); } } } class StreamGobber implements Runnable { private InputStream Pipe; public StreamGobber(InputStream pipe) { if(pipe == null) { throw new NullPointerException("bad pipe"); } Pipe = pipe; } public void run() { try { byte buffer[] = new byte[2048]; int read = Pipe.read(buffer); while(read >= 0) { System.out.write(buffer, 0, read); read = Pipe.read(buffer); } } catch (IOException e) { e.printStackTrace(); } finally { if(Pipe != null) { try { Pipe.close(); } catch (IOException e) { } } } } } Logo
支持版本: UCB Logo
SHELL命令返回列表：
print first butfirst shell [ls -a] ; ..
MAXScript
dosCommand "pause"
Objective-C
支持版本：苹果公司的GCC version 4.0.1
void runls() { [[NSTask launchedTaskWithLaunchPath:@"/bin/ls" arguments:[NSArray array]] waitUntilExit]; } 如果你希望调用系统命令，先执行shell：
void runSystemCommand(NSString *cmd) { [[NSTask launchedTaskWithLaunchPath:@"/bin/sh" arguments:[NSArray arrayWithObjects:@"-c", cmd, nil]] waitUntilExit]; } 同样可以使用上面的C语言调用方法。
OCaml
Sys.command "ls"
Perl
my @result = qx(ls); # runs command and returns its STDOUT my @results = `ls`; # dito, alternative syntax system "ls"; # runs command and returns its exit status print `ls`; #The same, but with back quotes exec "ls"; # replace current process with another
另外可以参阅 http://perldoc.perl.org/perlipc.html#Using-open()-for-IPC http://perldoc.perl.org/IPC/Open3.html
PHP
首行执行命令，第二行显示输出：
@exec($command,$output); echo nl2br($output);
注意这里的‘@’防止错误消息的显示，‘nl2br’ 将 ‘\n’转换为HTML的‘br’
Pop11
sysobey(’ls’);
Python
支持版本: Python version 2.5
import os code = os.system(’ls’) # Just execute the command, return a success/fail code output = os.popen(’ls’).read() # If you want to get the output data
或者
支持版本: Python version 2.4 (及以上版本)
import subprocess output = subprocess.Popen(’ls’, shell=True, stdout=subprocess.PIPE).stdout print output.read()
后者是比较好的方法。
或者
支持版本: Python version 2.2 (及以上版本)
import commands stat, out = commands.getstatusoutput(’ls’) if not stat: print out
Raven
`ls -la` as listing
或者指定任何字符串
‘ls -la’ shell as listing
Ruby
string = `ls`
Tcl
puts [exec ls]
同样可以使用系统open命令。
set io [open "|ls" r]
获取结果的方法是
set nextline [gets $io]
或者
set lsoutput [read $io]
如果命令是以RW方式打开，可以用同样的方法发送用户的输入。
Toka
needs shell
" ls" system
UNIX Shell
直接调用
ls
如果希望获取标准输出
CAPTUREDOUTPUT=$(ls)
在 C-Shell 中可以这样做
set MYCMDOUTPUT = `ls`
echo $MYCMDOUTPUT
在Korn Shell 中是这样:
MYCMDOUTPUT=`ls`
echo $MYCMDOUTPUT