There are three main methods to edit files under UNIX
1. Use a command line editor like vi or emacs or the GCG SeqEd or IG sequence editor.
These editors are popular because they are FAST. You can open up a multimegabyte text file, edit it and save the results in less time that it would take to open the file using Microsoft Word.
2. Use a X-Window graphical editor (xedit, textedit, GCG SeqLab or GDE editor)
These programs are popular because they have a graphical user interface like you would find on Macintosh or Windows editors.
3. Edit the file on the Mac or PC and copy to your UNIX account