...FYI, I tried this approach on my own system and I reproduced the problem.

But what I found is that I had supplied bad path names. When I used correct path names in my experiment, the code you supplied worked fine.

The differences in my setup were that I created directories as you showed, but mine were beneath my home directory rather than immediately below the root directory. Otherwise, everything else was probably the same.

Here's what I did:

$ mkdir main22 main23
$ mkdir main22/loges main23/loge
$ echo "john\nfile2" >main22/loges/de.pl
$ echo "john1\nfile3" >main23/loge/do.pl 
$ grep file2 /home/flame/main23/loge/do.pl /home/flame/main22/loges/de
+.pl  
$ perl -e 'system qq{grep file2 /home/flame16/main23/loge/do.pl /home/
+flame16/main22/loges/de.pl}'
[download]

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