Some, shells have an option (as an extension to the standards) that does remove globbing patterns that do not match any existing files. For instance, if you are using a recent bash, the code:

Code:

shopt -s nullglob
for i in N???
do	printf '%s\n' "$i"
done

would not run the loop at all if N??? does not match any files in the current working directory, while the other options work with any shell based on Bourne shell syntax:

Code:

for i in N???
do	if [ "$i" = "N???" ]
	then	break
	fi
	printf '%s\n' "$i"
done

which works fine as long as you know that there will never be a file actually named N???. (Note that the break could be replaced by a continue and get the same results.) Or, you can use:

Code:

for i in N???
do	if [ -e "$i" ]
	then	continue
	fi
	printf '%s\n' "$i"
done

(Note that you need to use continue in this form (not break) to protect yourself in case a file is removed while the loop is running (you just want to skip processing the file that was removed; not skip processing other remaining files with names that sort after the file that was removed).