24 種語言執行外部命令的方法
在這個例子中展示用不同語言調用外部命令的方法。覺得這個挺有意思，轉來給大家看看，也許某一天你會覺得有用。
這些語言包括
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
平臺: 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
帶屏幕輸出的 "ls" ：
$ls
將輸出保存到數組"result"：
spawn,"ls",result
異步執行，將輸出轉到LUN "unit"，以便在以后讀取：
spawn,"ls",unit=unit
J
J語言系統命令界面由標準的"task"腳本提供：
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+
有兩種執行系統命令的方法，簡單的方法會掛起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) {
}
}
}
}
} 正確的方法使用進程提供的線程去讀取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：蘋果公司的GCC version 4.0.1
void runls()
{
[[NSTask launchedTaskWithLaunchPath:@"/bin/ls"
arguments:[NSArray array]] waitUntilExit];
} 如果你希望調用系統命令，先執行shell：
void runSystemCommand(NSString *cmd)
{
[[NSTask launchedTaskWithLaunchPath:@"/bin/sh"
arguments:[NSArray arrayWithObjects:@"-c", cmd, nil]]
waitUntilExit];
} 同樣可以使用上面的C語言調用方法。
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
另外可以參閱 http://perldoc.perl.org/perlipc.html#Using-open()-for-IPC http://perldoc.perl.org/IPC/Open3.html
PHP
首行執行命令，第二行顯示輸出：
@exec($command,$output); echo nl2br($output);
注意這里的‘@’防止錯誤消息的顯示，‘nl2br’ 將 ‘\n’轉換為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()
后者是比較好的方法。
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]
同樣可以使用系統open命令。
set io [open "|ls" r]
獲取結果的方法是
set nextline [gets $io]
或者
set lsoutput [read $io]
如果命令是以RW方式打開，可以用同樣的方法發送用戶的輸入。
Toka
needs shell
" ls" system
UNIX Shell
直接調用
ls
如果希望獲取標準輸出
CAPTUREDOUTPUT=$(ls)
在 C-Shell 中可以這樣做
set MYCMDOUTPUT = `ls`
echo $MYCMDOUTPUT
在Korn Shell 中是這樣:
MYCMDOUTPUT=`ls`
echo $MYCMDOUTPUT