MySQL Reference Manual :: A.3.3 Problems with File Permissions

If you have problems with file permissions, the UMASK environment variable might be set incorrectly when mysqld starts. For example, MySQL might issue the following error message when you create a table:

ERROR: Can't find file: 'path/with/filename.frm' (Errcode: 13)

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> mysqld_safe &

By default, MySQL creates database and RAID directories with an access permission value of 0700. You can modify this behavior by setting the UMASK_DIR variable. If you set its value, new directories are created with the combined UMASK and UMASK_DIR values. For example, if you want to give group access to all new directories, you can do this:

shell> UMASK_DIR=504  # = 770 in octal
shell> export UMASK_DIR
shell> mysqld_safe &

In MySQL 3.23.25 and above, MySQL assumes that the value for UMASK and UMASK_DIR is in octal if it starts with a zero.

See Appendix F, Environment Variables.