5.1.4.2. File attribute checking

Table 5-2. File attribute operators

Operator	True if...
-a file	file exists
-d file	file exists and is a directory
-e file	file exists; same as - a
-f file	file exists and is a regular file (i.e., not a directory or other special type of file)
-r file	You have read permission on file
-s file	file exists and is not empty
-w file	You have write permission on file
-x file	You have execute permission on file, or directory search permission if it is a directory
-N file	file was modified since it was last read
-O file	You own file
-G file	file 's group ID matches yours (or one of yours, if you are in multiple groups)
file1 -nt file2	file1 is newer than file2 [6]
file1 -ot file2	file1 is older than file2

^[6] Specifically, the -nt and -ot operators compare modification times of two files.