-r file    True if the file exists (is accessible) and is readable.

-w file    True if the file exists and is writable.

-x file    True if the file exists and has execute permission.

-e file    True if the file exists.

-f file    True if the file exists and is a plain file.

-d file    True if the file exists and is a directory.

-s file    True if the file exists and has a size greater than zero.

-t fildes  True if the open file whose file descriptor number is fildes (1 by default) is the  same  file
           as /dev/cons.

-A file    True if the file exists and is append-only.

-L file    True if the file exists and is exclusive-use.

-Tfile     True if the file exists and is temporary.

s1 = s2    True if the strings s1 and s2 are identical.

-n s1      True if the length of string s1 is non-zero.

-z s1      True if the length of string s1 is zero.

-o        binary or operator

-a        binary and operator; higher precedence than -o