File Manager activities require a considerable amount of text processing.
Microsoft Windows
This can be done with the two programs provided by Windows, TextPad and WordPad. However, these programs have several limitations, and there are Shareware programs which do the job much better.
The best text processor currently available is NoteTab. It is feature rich, easy to use, and well supported. It comes in three versions:
NoteTab Light
Handle many files simultaneously with a tabbed interface. Search files, strip HTML tags and format text quickly. Formerly called "Super NoteTab". 100% freeware -- no ads and no nags.
NoteTab Std
Same as NoteTab Light, but adds several features like a thesaurus, a multilingual spell checker, text-outline editing, Clipbars, etc. $9.95 US.
NoteTab Pro
NoteTab Pro offers all the features HTML authors, programmers, and other demanding users need to speed up their work. The registered version adds a thesaurus and a spell checker. Of special note to File Managers, the Pro edition lets you format text files to a specified line length, a big time saver. $19.95 US.
The Pro version of this program is highly recommended. You will find many uses for this program in addition to your File Manager activities.
Available at: http://www.notetab.com/
A search at Tucows for text editors finds 300 different programs. Some of these may have features or an interface that you like better:
http://tucows.epix.net/index.html
Apple
SimpleText will suffice as a text editor for Macintosh. Older versions of Microsoft Word (up to 5.1) also work well. The default on later versions of Word (Office 98, Office 2000, or Word 6) is to open html documents as they will appear on the web, not as text, which makes them less convenient to use for many of the text-processing chores associated with the file manager's job. They are useful however for opening files sent to you in document formats, and converting them to plain text.
While SimpleText will do the job, a more full featured text editor will make your work easier. One of the better shareware products is Tex-Edit Plus. Full details and a downloadable copy can be found at:
http://www.nearside.com/trans-tex/