脚本中的Unix Comm无法正常工作

Question

我有这个下面的脚本，计划按小时进行一次cron计划，以查看在什么时候进行了几次新的失败尝试。

[root@server123 abc123]# cat script
#!/bin/bash
# Checks if the log file exists
if [ ! -e Internal_LogFile ] ; then
grep "Authentication <failed> for <Active Directory> user: <xyz123>" secure.log > Internal_LogFile
else
#> Internal_LogFile
comm -23 <(grep "Authentication <failed> for <Active Directory> user: <xyz123>" secure.log | sort) <(sort Internal_LogFile) > Internal_LogFile
fi
[root@server123 abc123]#

我们寻找secure.log文件，在其中可以看到失败尝试日志条目。我打算单独捕获那些具有特定ID的对象，然后将这些条目保存在一个名为Internal_LogFile的新文件中。并计划在邮件中转发此Internal_LogFile。

这是我到目前为止尝试过的，如果您看到secure.log-出现1条失败条目。

[root@server123 abc123]# cat secure.log
1st line
2nd line
Authentication <failed> for <Active Directory> user: <xyz123>
[root@server123 abc123]#

运行脚本后，我得到了预期的结果

[root@server123 abc123]# bash script
[root@server123 abc123]# ls
Internal_LogFile  script  secure.log
[root@server123 abc123]# cat Internal_LogFile
Authentication <failed> for <Active Directory> user: <xyz123>
[root@server123 abc123]#

但是当secure.log用下一个失败日志更新时，我打算的输出只是新的，因此我使用comm＆sort，然后将新的输出覆盖到文件中。

[root@server123 abc123]# echo -e "4th line\n5th line\n6th line Authentication <failed> for <Active Directory> user: <xyz123>" >> secure.log
[root@server123 abc123]# cat secure.log
1st line
2nd line
Authentication <failed> for <Active Directory> user: <xyz123>
4th line
5th line
6th line Authentication <failed> for <Active Directory> user: <xyz123>
[root@server123 abc123]#

当我手动运行它时，我只会看到想要的结果，

[root@server123 abc123]# comm -23 <(grep "Authentication <failed> for <Active Directory> user: <xyz123>" secure.log | sort) <(sort Internal_LogFile)
6th line Authentication <failed> for <Active Directory> user: <xyz123> 

但是当我执行此操作时，它不会覆盖文件，尽管我没有在脚本中附加>>，它只是>。

[root@server123 abc123]# bash script
[root@server123 abc123]#
[root@server123 abc123]# cat Internal_LogFile
6th line Authentication <failed> for <Active Directory> user: <xyz123>
Authentication <failed> for <Active Directory> user: <xyz123>

当前代码：

[root@server123 abc123]# cat script
#!/bin/bash
# Checks if the log file exists
if [ ! -e Internal_LogFile ] ; then
grep "Authentication <failed> for <Active Directory> user: <xyz123>" secure.log > Internal_LogFile
else
comm -23 <(grep "Authentication <failed> for <Active Directory> user: <xyz123>" secure.log | sort) <(sort Internal_LogFile) > Internal_LogFile
fi
[root@server123 abc123]#