`-a FILE'
True if FILE exists.

`-b FILE'
True if FILE exists and is a block special file.

`-c FILE'
True if FILE exists and is a character special file.

`-d FILE'
True if FILE exists and is a directory.

`-e FILE'
True if FILE exists.

`-f FILE'
True if FILE exists and is a regular file.

`-g FILE'
True if FILE exists and its set-group-id bit is set.

`-h FILE'
True if FILE exists and is a symbolic link.

`-k FILE'
True if FILE exists and its "sticky" bit is set.

`-p FILE'
True if FILE exists and is a named pipe (FIFO).

`-r FILE'
True if FILE exists and is readable.

`-s FILE'
True if FILE exists and has a size greater than zero.

`-t FD'
True if file descriptor FD is open and refers to a terminal.

`-u FILE'
True if FILE exists and its set-user-id bit is set.

`-w FILE'
True if FILE exists and is writable.

`-x FILE'
True if FILE exists and is executable.

`-z STRING'
True if the length of STRING is zero.

`-n STRING'
`STRING'
True if the length of STRING is non-zero.

`STRING1 == STRING2'
True if the strings are equal. `=' may be used in place of `=='
for strict POSIX compliance.

`STRING1 != STRING2'
True if the strings are not equal.

`STRING1 < STRING2'
True if STRING1 sorts before STRING2 lexicographically in the
current locale.

`STRING1 > STRING2'
True if STRING1 sorts after STRING2 lexicographically in the
current locale.

`ARG1 OP ARG2'
`OP' is one of `-eq', `-ne', `-lt', `-le', `-gt', or `-ge'. These
arithmetic binary operators return true if ARG1 is equal to, not
equal to, less than, less than or equal to, greater than, or
greater than or equal to ARG2, respectively. ARG1 and ARG2 may be
positive or negative integers.