If you have problems with file permissions, for example, if mysql issues the following error message when you create a table:
ERROR: Can't find file: 'path/with/filename.frm' (Errcode: 13)
then the environment variable UMASK might be set incorrectly when mysqld starts up. The default umask value is 0660. You can change this behavior by starting mysqld_safe as follows:
shell> UMASK=384 # = 600 in octal shell> export UMASK shell> /path/to/mysqld_safe &
By default MySQL will create database and RAID directories with permission type 0700. You can modify this behavior by setting the UMASK_DIR variable. If you set this, new directories are created with the combined UMASK and UMASK_DIR. For example, if you want to give group access to all new directories, you can do:
shell> UMASK_DIR=504 # = 770 in octal shell> export UMASK_DIR shell> /path/to/mysqld_safe &
In MySQL Version 3.23.25 and above, MySQL assumes that the value for UMASK and UMASK_DIR is in octal if it starts with a zero.