Group and count files by type in Perl (using file magic numbers)¶
Perl File::Find - passing parameters to „wanted” callback - basics¶
Using object oriented libraries with File::Find module is not so obvious like it should be. But there is a way to do it in simple way - use closures in Perl. Now you probably think, „stop the bla bla talk, and show me code!”, so here it is:
How to determine file type ignoring extension?¶
Answer is simple - using magic numbers.
What is magic number¶
The term magic number is a constant numerical or text value used to identify a file format or protocol.
How connect file type with magic number in Perl?¶
There is variety of modules implementing this, for sample application
presented below I have used File::Type module.
Installation of this module on Ubuntu is extreme easy: apt-get install libfile-type-perl.
Tool for finding files of certain type using magic numbers¶
Here you can download source code of this program: findGroup.pl
How to use the tool?¶
$ perl findGroup.pl .
Directory . contains:
17 application/octet-stream
2 application/x-perl
3 application/zip
346 image/jpeg
$ perl findGroup.pl . perl
2 files of type application/x-perl (matching: perl) in .
./findGroup.pl
./test.pl
Additional references:¶
How do I pass parameters to the File::Find subroutine that processes each file? StackOverflow[1] StackOverflow[1]