4.2.3. Specifying Program Options
Options are processed in order, so if an option is specified multiple times, the last occurrence takes precedence. The following command causes mysql to connect to the server running on localhost:
shell> mysql -h example.com -h localhost
If conflicting or related options are given, later options take precedence over earlier options. The following command runs mysql in “no column names” mode:
shell> mysql --column-names --skip-column-names
MySQL programs determine which options are given first by examining environment variables, then by reading option files, and then by checking the command line. This means that environment variables have the lowest precedence and command-line options the highest.
You can take advantage of the way that MySQL programs process options by specifying default option values for a program in an option file. That enables you to avoid typing them each time you run the program while enabling you to override the defaults if necessary by using command-line options.
An option can be specified by writing it in full or as any unambiguous prefix. For example, the --compress option can be given to mysqldump as --compr, but not as --comp because the latter is ambiguous:
shell> mysqldump --comp
mysqldump: ambiguous option '--comp' (compatible, compress)
Be aware that the use of option prefixes can cause problems in the event that new options are implemented for a program. A prefix that is unambiguous now might become ambiguous in the future.
As of MySQL 5.5.33, unambiguous prefixes are deprecated. If an unambiguous prefix is given, a warning occurs to provide feedback. Option prefixes are no longer supported in MySQL 5.7; only full options are accepted.