調用系統（）或perl的IPC :: RUN3命令似乎並沒有通過環境變量（$ ENV {JAVA_HOME}）

Question

我一直在利用Perl啓動Java進程中掙扎。該問題的根源在於，java程序缺少JAVA_HOME環境變量引起ClassNotFoundException。

我開始用IPC::Run3，因爲它的標準輸入/輸出的相對優雅的重定向。

假設IPC::Run3會使用%ENV，我試着加入$ENV{JAVA_HOME}。

如果沒有工作，我想這樣做system()。沒有工作，所以最後，我把它用system("JAVA_HOME=/path/to/java && /path/to/java_program");

我的測試程序是下面工作。當然，我會取消註釋適當的塊來測試適當的調用。

#!/usr/bin/perl -w 
use strict; 

use IPC::Run3; 

use vars qw(%Config $nutch_stdout $nutch_stderr); 

%Config = (
    'nutch_binary'  => q[/home/crawl/nutch/runtime/local/bin/nutch], 
    'nutch_crawl_dir' => q[/home/crawl/nutch-crawl/crawl/crawldb/current/part-00000], 
    'nutch_seed_dir'  => q[/home/crawl/urls], 
    'solr_url'   => q[http://localhost:8080/solr], 
); 

my @nutch_command = ("$Config{nutch_binary}", 
       "crawl $Config{nutch_seed_dir}", 
       "-solr $Config{solr_url}", 
       "-d $Config{nutch_crawl_dir}", 
       "-threads 1", 
       "-depth 1"); 

$ENV{JAVA_HOME}  = '/usr/lib/jvm/java-1.6.0'; 

while ((my $key,my $value) = each %ENV) { 
    print "$key=$value\n"; 
} 

print "Running @nutch_command\n"; 

# My original code. Next few lines are shown in first batch of output below. 
#run3 \@nutch_command, undef, \$nutch_stdout, \$nutch_stderr; 
#print "Output from Nutch:\n"; 
#print $nutch_stdout; 
#print "Errors from Nutch:\n"; 
#print $nutch_stderr; 

# Second try. The next line's output is the second batch of output. 
#system(@nutch_command); 

# Third try. Despite setting and displaying %ENV, this is the only thing I tried that worked 
system("JAVA_HOME=/usr/lib/jvm/java-1.6.0 && @nutch_command"); 

這裏的運行RUN3的輸出：

-bash-3.2$ ./test.pl 
    ... [snip] ... 
    JAVA_HOME=/usr/lib/jvm/java-1.6.0 
    ... [snip] ... 
    Running /home/crawl/nutch/runtime/local/bin/nutch crawl /home/crawl/urls -solr http://localhost:8080/solr -d /home/crawl/nutch-crawl/crawl/crawldb/current/part-00000 -threads 1 -depth 1 
    Output from Nutch: 
    Errors from Nutch: 
    Exception in thread "main" java.lang.NoClassDefFoundError: crawl 
    Caused by: java.lang.ClassNotFoundException: crawl 
at java.net.URLClassLoader$1.run(URLClassLoader.java:217) 
at java.security.AccessController.doPrivileged(Native Method) 
at java.net.URLClassLoader.findClass(URLClassLoader.java:205) 
at java.lang.ClassLoader.loadClass(ClassLoader.java:321) 
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294) 
at java.lang.ClassLoader.loadClass(ClassLoader.java:266) 
    Could not find the main class: crawl. Program will exit. 

而且第一個系統的輸出（）調用：

-bash-3.2$ ./test.pl 
    ... [snip] ... 
    JAVA_HOME=/usr/lib/jvm/java-1.6.0 
    ... [snip] ... 
    Running /home/crawl/nutch/runtime/local/bin/nutch crawl /home/crawl/urls -solr http://localhost:8080/solr -d /home/crawl/nutch-crawl/crawl/crawldb/current/part-00000 -threads 1 -depth 1 
    Exception in thread "main" java.lang.NoClassDefFoundError: crawl 
    Caused by: java.lang.ClassNotFoundException: crawl 
at java.net.URLClassLoader$1.run(URLClassLoader.java:217) 
at java.security.AccessController.doPrivileged(Native Method) 
at java.net.URLClassLoader.findClass(URLClassLoader.java:205) 
at java.lang.ClassLoader.loadClass(ClassLoader.java:321) 
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294) 
at java.lang.ClassLoader.loadClass(ClassLoader.java:266) 
    Could not find the main class: crawl. Program will exit. 

最後，第三個系統call--唯一一個工作 - 與環境變量設置在線：

-bash-3.2$ ./test.pl 
    ... [snip] ... 
    JAVA_HOME=/usr/lib/jvm/java-1.6.0 
    ... [snip] ... 
    Running /home/crawl/nutch/runtime/local/bin/nutch crawl /home/crawl/urls -solr http://localhost:8080/solr -d /home/crawl/nutch-crawl/crawl/crawldb/current/part-00000 -threads 1 -depth 1 
    crawl started in: crawl-20120216133832 
    ... continue success stdout output 

最後一個問題：除了有設置在線環境與系統（）調用，什麼對環境無功傳遞給IPC :: RUN3或系統的正確方法（）調用？

（注：％ENV的輸出被截斷，只相關的行......行像PATH，SHELL，_等不相關的省略問題）

在情況下，它是相關的：

-bash-3.2$ uname -a 
Linux hostname 2.6.18-238.el5xen #1 SMP Thu Jan 13 16:41:45 EST 2011 x86_64 x86_64 x86_64 GNU/Linux 
-bash-3.2$ perl --version 
This is perl, v5.8.8 built for x86_64-linux-thread-multi 

Answer 1

The root of the problem is that the java process is missing the JAVA_HOME environment variable causing a ClassNotFoundException.

REVISED

這不是問題的根源。實際上，Java本身不需要設置JAVA_HOME。

問題的直接原因是下列之一：

• 封裝器沒有設置類路徑正確地爲您嘗試執行應用程序。

• 使用了錯誤的類名的包裝。類名「nutch」是不尋常的和可疑的 - 沒有包名。

看起來真正的根本原因可能是您正在錯誤地組裝參數列表。其中每一個帶有空格的參數都應該是兩個參數;即

 my @nutch_command = ("$Config{nutch_binary}", 
      "crawl", "$Config{nutch_seed_dir}", 
      "-solr", "$Config{solr_url}", 
      "-d", "$Config{nutch_crawl_dir}", 
      "-threads", "1", 
      "-depth", "1"); 

我懷疑這混淆了Nutch的包裝腳本，並造成其使用了錯誤的類名（除其他事項外）。當你將整個命令作爲一個字符串傳遞並讓shell解析它時，問題（自然而然）就會消失。