Bash Params

Bash utils:

File tests

This section probably holds the most tests, I'll list them in some logical order. Since Bash 4.1, all tests related to permissions respect ACLs, if the underlying filesystem/OS supports them.

Operator syntax	Description
-a	True if exists. (not recommended, may collide with -a for AND, see below)
-e	True if exists.
-f	True, if exists and is a regular file.
-d	True, if exists and is a directory.
-c	True, if exists and is a character special file.
-b	True, if exists and is a block special file.
-p	True, if exists and is a named pipe (FIFO).
-S	True, if exists and is a socket file.
-L	True, if exists and is a symbolic link.
-h	True, if exists and is a symbolic link.
-g	True, if exists and has sgid bit set.
-u	True, if exists and has suid bit set.
-r	True, if exists and is readable.
-w	True, if exists and is writable.
-x	True, if exists and is executable.
-s	True, if exists and has size bigger than 0 (not empty).
-t	True, if file descriptor is open and refers to a terminal.
-nt	True, if is newer than (mtime).
-ot	True, if is older than (mtime).
-ef	True, if is a hardlink to .

String tests

Operator syntax	Description
-z	True, if is empty.
-n	True, if is not empty (this is the default operation).
=	True, if the strings are equal.
!=	True, if the strings are not equal.
<	True if sorts before lexicographically (pure ASCII, not current locale!). Remember to escape! Use \<
>	True if sorts after lexicographically (pure ASCII, not current locale!). Remember to escape! Use \>

Arithmetic tests

Operator syntax	Description
-eq	True, if the integers are equal.
-ne	True, if the integers are NOT equal.
-le	True, if the first integer is less than or equal second one.
-ge	True, if the first integer is greater than or equal second one.
-lt	True, if the first integer is less than second one.
-gt	True, if the first integer is greater than second one.

Misc syntax

Operator syntax	Description
-a	True, if and are true (AND). Note that -a also may be used as a file test (see above)
-o	True, if either or is true (OR).
!	True, if is false (NOT).
( )	Group a test (for precedence). Attention: In normal shell-usage, the "(" and ")" must be escaped; use "\(" and "\)"!
-o	True, if the shell option is set.
-v	True if the variable has been set. Use var[n] for array elements.
-R	True if the variable has been set and is a nameref variable (since 4.3-alpha)

Copied from here