Open a large XML file
Depending on the source of the file, you may wish to investigate its contents in other ways than just opening it (double clicking).  For this, you should use the command line.

Some suggested starting points (where "whatever.xml" is the name of the file):

file whatever.xml


This will tell you what type the file is.  Not by file extension, but by actual examination of the contents.

head whatever.xml


This will show you the first ten lines of the file.  However, be warned: It is possible to have an entire 50 MB XML file consisting of a single line.  Press Ctrl-C to stop if it starts spewing garbage.  (Yes, Control C, not Command-C.)

To just view the file without even the possibility of editing it:

less whatever.xml


If the file does consist of very long lines, for reading it, you could force periodic line wraps (formatting):

fmt whatever.xml | less


But actually, less will wrap the lines by default unless you tell it not to.  For no wrapping of lines (so you can use sideways arrow keys to scroll):

less -S whatever.xml




It is a good probability that one of these commands will disclose a problem with the file.