动态建立在bash命令 [英] Dynamically building a command in bash

问题描述

我在bash动态construcing的命令。这工作得很好：

I am construcing a command in bash dynamically. This works fine:

COMMAND="java myclass"
${COMMAND}

现在我要动态地构建redirectes输出的命令：

Now I want to dynamically construct a command that redirectes the output:

LOG=">> myfile.log 2>&1"
COMMAND="java myclass $LOG"
${COMMAND}

该命令还调用java程序，但输出不重定向到myfile.log

The command still invokes the java process, but the output is not redirected to myfile.log

此外，如果我做的：

BACKGROUND="&"
COMMAND="java myclass $BACKGROUND"
${COMMAND}

该命令在后台运行。

The command isn't run in the background.

如何让日志重定向和背景位工作任何线索？ （bash的-x显示正在构建的命令如预期）

Any clues on how to get the log redirect, and background bits working? (bash -x shows the commands being constructed as expected)

（在现实中，不象本实施例中，LOG和背景的值被动态地设置）

(In reality, unlike this example, the values of LOG and BACKGROUND are set dynamically)

推荐答案

它不起作用，因为报价禁用的特殊含义＆GT; 和＆安培; 。您必须执行该实施外壳这些功能的命令。

It doesn't work because quotes disable the special meaning of > and &. You must execute the commands which implement these features of the shell.

要重定向，呼叫 EXEC＆GT;＆GT; myfile.log 2 - ;＆放大器; 1 要记录的命令之前

To redirect, call exec >> myfile.log 2>&1 before the command you want to log.

要在后台运行一个程序，使用的nohup （ CMD的nohup ARGS ... ）。

To run a program in the background, use nohup (nohup cmd args...).

这篇关于动态建立在bash命令的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！