Files that start with a dash can cause problems if you don't know how to deal with them. Let's take a look:
Chimera:Documents axon$ ls -1The file "-file.doc" will cause problems with most command-line tools because they think -file.doc is an argument, not a file name.
Chimera:Documents axon$ cat -file.docSee what I mean?
cat: illegal option -- f
usage: cat [-benstuv] [file ...]
Chimera:Documents axon$ rm -file.doc
rm: illegal option -- l
usage: rm [-f | -i] [-dPRrvW] file ...
Chimera:Documents axon$ mv -file.doc file.doc
mv: illegal option -- l
usage: mv [-f | -i | -n] [-v] source target
mv [-f | -i | -n] [-v] source ... directory
Placing two dashes anywhere in the argument list of almost every shell utility will tell that utility that all of the optional arguments have been passed and that anything following the double dash is to be taken literally -- usually this means it's a filename*. This lets you manipulate files that would otherwise cause you problems.
Chimera:Documents axon$ cat -- -file.docFor clarity, I used ls -1 (the number one not the lowercase letter "L" ) to force output to one filename per line.
this is a test file.
Chimera:Documents axon$ mv -- -file.doc file.doc
Chimera:Documents axon$ ls -1
* For certain things, the literal arguments are passed on to a separate utility or script. A good example of this: Most startx scripts process command-line arguments, but you can use -- to pass additional arguments directly to the X Server, untouched by the startx script.