Syntax: aio_write on | off; Default: aio_write off; Context: http, server, location This directive appeared in version 1.9.13. If aio is enabled, specifies whether it is used for writing files. Currently, this only works when using aio threads and is limited to writing temporary files with data received from proxied servers.

Syntax: aio on | off | threads[=pool]; Default: aio off; Context: http, server, location This directive appeared in version 0.8.11. Enables or disables the use of asynchronous file I/O (AIO) on FreeBSD and Linux: location /video/ { aio on; output_buffers 1 64k; } On FreeBSD, AIO can be used starting from FreeBSD 4.3. Prior to FreeBSD 11.0, AIO can either be linked statically into a kernel: options VFS_AIO or loaded dynamically as a kernel lo

Syntax: add_header name value [always]; Default: — Context: http, server, location, if in location Adds the specified field to a response header provided that the response code equals 200, 201, 204, 206, 301, 302, 303, 304, or 307. A value can contain variables. There could be several add_header directives. These directives are inherited from the previous level if and only if there are no add_header directives defined on the current level. If the always parameter is specified

Syntax: add_before_body uri; Default: — Context: http, server, location Adds the text returned as a result of processing a given subrequest before the response body. An empty string ("") as a parameter cancels addition inherited from the previous configuration level.

Syntax: add_after_body uri; Default: — Context: http, server, location Adds the text returned as a result of processing a given subrequest after the response body. An empty string ("") as a parameter cancels addition inherited from the previous configuration level.

Syntax: addition_types mime-type ...; Default: addition_types text/html; Context: http, server, location This directive appeared in version 0.7.9. Allows adding text in responses with the specified MIME types, in addition to “text/html”. The special value “*” matches any MIME type (0.8.29).

Syntax: access_log path format [buffer=size] [gzip[=level]] [flush=time] [if=condition];access_log off; Default: access_log off; Context: stream, server Sets the path, format, and configuration for a buffered log write. Several logs can be specified on the same level. Logging to syslog can be configured by specifying the “syslog:” prefix in the first parameter. The special value off cancels all access_log directives on the current level. If either the buf

Syntax: access_log path [format [buffer=size] [gzip[=level]] [flush=time] [if=condition]];access_log off; Default: access_log logs/access.log combined; Context: http, server, location, if in location, limit_except Sets the path, format, and configuration for a buffered log write. Several logs can be specified on the same level. Logging to syslog can be configured by specifying the “syslog:” prefix in the first parameter. The special value off cancels all ac

Syntax: accept_mutex_delay time; Default: accept_mutex_delay 500ms; Context: events If accept_mutex is enabled, specifies the maximum time during which a worker process will try to restart accepting new connections if another worker process is currently accepting new connections.

Syntax: accept_mutex on | off; Default: accept_mutex off; Context: events If accept_mutex is enabled, worker processes will accept new connections by turn. Otherwise, all worker processes will be notified about new connections, and if volume of new connections is low, some of the worker processes may just waste system resources. There is no need to enable accept_mutex on systems that support the EPOLLEXCLUSIVE flag (1.11.3) or when using reuseport. Prior to version 1.11.3, the