Operator Meaning
-r Returns true if this file is readable by the effective ID (user ID and group ID).
-w Returns true if this file is writable by the effective ID (user ID and group ID).
-x Returns true if this file is executable by the effective ID (user ID and group ID).
-o Returns true if this file is owned by the effective ID (user ID and group ID).
-R Returns true if this file is readable by the login ID (real user ID and group ID).
-W Returns true if this file is writable by the login ID (real user ID and group ID).
-X Returns true if this file is executable by the login ID (real user ID and group ID).
-O Returns true if this file is owned by the login ID (real user ID and group ID).