mysqladmin ping error code

Question

Mysqladmin ping returns 0 even with a password failure, a thing that mysqlclient doesn't. Is this a mistake from Mysqladmin Developpers? I don't understand why Mysqladmin is asking for a login/password because it returns 0 even if you don't specify a login.

If I try a Mysqladmin ping without any login/password :

# mysqladmin ping ; echo $?

mysqladmin: connect to server at 'localhost' failed
error: 'Access denied for user 'root'@'localhost' (using password: NO)'
0

Mysqladmin give me a login error and tells me that the server is currently running (0 value) so why asking for a login if it still gives me the answer?

When I do something like this :

#mysqladmin -uroot -pWrongPassword ping ; echo $?

mysqladmin: connect to server at 'localhost' failed
error: 'Access denied for user 'root'@'localhost' (using password: YES)'
0

This return me 0 instead of 1.

Now if I stop mysql server and try again :

# mysqladmin -uroot -pWrongPassword ping ; echo $?

mysqladmin: connect to server at 'localhost' failed
error: 'Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)'
Check that mysqld is running and that the socket: '/var/run/mysqld/mysqld.sock' exists!
1

It gives me the proper value because the server is stopped, we dont care about the wrong password.

Finally i did the same test with Mysqlclient and a wrongpassword :

# mysql -uroot -pWrongPassword mysql -sN -e "select * from user" ; echo $?

ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
1

I know that the main purpose of this command is to test the availability of the mysql server but ask for a login/password doesn't make any sense if you still give the 0 value.

Do you think it is a bug?

Answer 1

It's not a bug. This behavior is by design.

ping
Check whether the server is available. The return status from mysqladmin is 0 if the server is running, 1 if it is not. This is 0 even in case of an error such as Access denied, because this means that the server is running but refused the connection, which is different from the server not running.