Unix Signal Handling in MySQL directory on Windows and  $HOME/.mylogin.cnf  on non-Windows systems. See Section 4.6.7, “mysql_config_editor — MySQL Configuration Utility” . The  MYSQL_TEST_TRACE_DEBUG  and  MYSQL_TEST_TRACE_CRASH  variables control the test protocol trace client plugin, if MySQL is built with that plugin enabled. For more information, see Using the Test Protocol Trace Plugin. The default  UMASK  and  UMASK_DIR  values are  0640  and  0750 , respectively. MySQL assumes that the value for  UMASK  or  UMASK_DIR  is in octal if it starts with a zero. For example, setting  UMASK=0600  is equivalent to  UMASK=384  because 0600 octal is 384 decimal. The  UMASK  and  UMASK_DIR  variables, despite their names, are used as modes, not masks: See also Section B.3.3.1, “Problems with File Permissions” . It may be necessary to set  PKG_CONFIG_PATH  if you use  pkg-config  for building MySQL programs. See Building C API Client Programs Using pkg-config. On Unix and Unix-like systems, a process can be the recipient of signals sent to it by the  root  system account or the system account that owns the process. Signals can be sent using the  kill  command. Some command interpreters associate certain key sequences with signals, such as  Control+C  to send a SIGINT  signal. This section describes how the MySQL server and client programs respond to signals. mysqld  responds to signals as follows: 634 Status information: Current dir: /var/mysql/data/ Running threads: 4 Stack size: 262144 Current locks: lock: 0x7f742c02c0e0: lock: 0x2cee2a20: : lock: 0x207a080: •If  UMASK  is set,  mysqld  uses  ($UMASK | 0600)  as the mode for file creation, so that newly created files have a mode in the range from 0600 to 0666 (all values octal). •If  UMASK_DIR  is set,  mysqld  uses  ($UMASK_DIR | 0700)  as the base mode for directory creation, which then is AND-ed with  ~(~$UMASK & 0666) , so that newly created directories have a mode in the range from 0700 to 0777 (all values octal). The AND operation may remove read and write permissions from the directory mode, but not execute permissions. •Server Response to Signals •Client Response to Signals • SIGTERM  causes the server to shut down. This is like executing a  SHUTDOWN  statement without having to connect to the server (which for shutdown requires an account that has the  SHUTDOWN  privilege). • SIGHUP  causes the server to reload the grant tables and to flush tables, logs, the thread cache, and the host cache. These actions are like various forms of the  FLUSH  statement. Sending the signal enables the flush operations to be performed without having to connect to the server, which requires a MySQL account that has privileges sufficient for those operations. Prior to MySQL 8.0.20, the server also writes a status report to the error log that has this format: Server Response to Signals 4.10 Unix Signal Handling in MySQL