File characteristic tests

These options test other file characteristics.

‘-e file’: True if file exists.
‘-s file’: True if file exists and has a size greater than zero.
‘file1 -nt file2’: True if file1 is newer (according to modification date) than file2, or if file1 exists and file2 does not.
‘file1 -ot file2’: True if file1 is older (according to modification date) than file2, or if file2 exists and file1 does not.
‘file1 -ef file2’: True if file1 and file2 have the same device and inode numbers, i.e., if they are hard links to each other.