a) filenames beginning with an 'x'

x*

b) filenames ending with an 'x'

*x

c) filenames containing an 'x', anywhere in the filename (multiple x's also match, e.g. xqcxnkxe is a match)

*x*

d) filenames beginning with a lowercase letter

[a-z]*

e) filenames containing one or more digits, anywhere in the file name

*[0-9]*