从应用程序调用时SED命令不生成输出文件 [英] SED command not generating output file when called from app

问题描述

我想编写一个Java程序，需要字符串Java和替换文本的相应序列在Perl脚本。这里是我的code：

I am trying to write a java program that takes Strings in Java and replaces corresponding sequences of text in a perl script. Here is my code:

    String sedFirstLine = "'s/AAA/"+newFirstLine+"/'";
    String sedNewCntr = "'s/BBB/"+newCntr+"/'";
    String sedNewSpacing = "'s/SPACE/"+newSpacing+"/'";
    String sedNewDmax = "'s/MAX/"+newDmax+"/'";
    String sedInputFile = "/filepath/myPerlScript.pl" 
    String sedOutputFile = "/filepath/myNewPerlScript.pl";
    String[] cmdArray3 = {"sed", "-e", sedFirstLine,"-e", sedNewCntr,"-e", sedNewSpacing,"-e", sedNewDmax, "-e", sedInputFile, ">", sedOutputFile};
    Process runCmd;
    runCmd = Runtime.getRuntime().exec(cmdArray3);

当我运行这个程序，是不是生成的输出文件myNewPerlScript.pl。我不知道什么是错的，我写的东西。我指的是早期的Java变量是newFirstLine，newCntr等。

When I run this program, the output file "myNewPerlScript.pl" is not generated. I'm not sure what is wrong with what I've written. The Java variables that I was referring to earlier are "newFirstLine", "newCntr", etc.

推荐答案

这是因为输出重定向（即＆GT; ）是shell的功能。为了重定向命令的输出，你可以用一个shell调用命令。例如，使用此命令

This is because the output redirection (i.e. the > ) is a functionality of the shell. In order to redirect the output of the command, you can invoke the command through a shell. For example, with this command

String[] cmdArray3 = {"bash", "-c", "sed 's/AAA/BBB/' inputfile > output"};
Process runCmd = Runtime.getRuntime().exec(cmdArray3);

如预期输出文件应该被创建。

the output file should be created as expected.

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