用grep&计数流程实例厕所 [英] Counting process instances with grep & wc

问题描述

我正在尝试使用以下命令对流程实例进行计数:

I am trying to count process instances using the following command:

$ ps -ef | grep "test.sh" | egrep -v "grep|vi|more|pg" | wc -l
1

这在命令行上可以完美地工作，但是在脚本中，当我将输出分配给变量时:

Which works perfectly on the command line, but in the script when I assign the output to a variable:

script_instances=`ps -ef | grep "test.sh" | egrep -v "grep|vi|more|pg" | wc -l`
echo $script_instances

输出:

2

它增加了1，我不知道为什么会发生.

It increments by 1, which I don't understand why it's happening.

如果我只是在脚本中放置以下命令，它将正确打印

If I just put following command in script it prints correctly

ps -ef | grep "test.sh" | egrep -v "grep"

输出:

root 14243 12162 0 19:12 pts/1 00:00:00 sh test.sh

我正在使用Ubuntu 14.04.5 LTS

I am on Ubuntu 14.04.5 LTS

推荐答案

不要使用grep foo | grep -v grep，当shell执行grep时，该grep foo | grep -v grep由grep处理，而是使用[ ]来获取您的脚本名称.

Don't use grep foo | grep -v grep, that gets processed by grep when the shell executes grep, instead use [ ] to get the pattern of your script name.

$ ps -ef | grep -c '[te]st.sh'

-c counts the number of matches

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