Apache Module mod_log_config

CustomLog with format nickname LogFormat "%h %l %u %t \"%r\" %>s %b" common CustomLog logs/access_log common

CustomLog with explicit format string CustomLog logs/access_log "%h %l %u %t \"%r\" %>s %b"

This module provides for flexible logging of client requests. Logs are written in a customizable format, and may be written directly to a file, or to an external program. Conditional logging is provided so that individual requests may be included or excluded from the logs based on characteristics of the request.

to define a log file and format in one step. The CustomLogTransferLog

directives can be used multiple times in each server to cause each request to be logged to multiple files.

directives is a string. This string is used to log each request to the log file. It can contain literal characters copied into the log files and the C-style control characters "\n" and "\t" to represent new-lines and tabs. Literal quotes and backslashes should be escaped with backslashes.CustomLog

The characteristics of the request itself are logged by placing "%

" directives in the format string, which are replaced in the log file by the values as follows:

| Format String | Description | |||||||||| |---|---|---|---|---|---|---|---|---|---|---|---| %% | The percent sign. | |||||||||| %a | Client IP address of the request (see the module). | |||||||||| %{c}a | Underlying peer IP address of the connection (see the module). | |||||||||| %A | Local IP-address. | |||||||||| %B | Size of response in bytes, excluding HTTP headers. | |||||||||| %b | Size of response in bytes, excluding HTTP headers. In CLF format, i.e. a '- ' rather than a 0 when no bytes are sent. | |||||||||| %{ | The contents of cookie VARNAME in the request sent to the server. Only version 0 cookies are fully supported. | |||||||||| %D | The time taken to serve the request, in microseconds. | |||||||||| %{ | The contents of the environment variable VARNAME. | |||||||||| %f | Filename. | |||||||||| %h | Remote hostname. Will log the IP address if is set to Off , which is the default. If it logs the hostname for only a few hosts, you probably have access control directives mentioning them by name. See | |||||||||| %H | The request protocol. | |||||||||| %{ | The contents of header line(s) in the request sent to the server. Changes made by other modules (e.g. ) affect this. If you're interested in what the request header was prior to when most modules would have modified it, use to copy the header into an internal environment variable and log that value with the %{ described above. | |||||||||| %k | Number of keepalive requests handled on this connection. Interesting if is being used, so that, for example, a '1' means the first keepalive request after the initial one, '2' the second, etc...; otherwise this is always 0 (indicating the initial request). | |||||||||| %l | Remote logname (from identd, if supplied). This will return a dash unless is present and is set On . | |||||||||| %L | The request log ID from the error log (or '-' if nothing has been logged to the error log for this request). Look for the matching error log line to see what request caused what error. | |||||||||| %m | The request method. | |||||||||| %{ | The contents of note VARNAME from another module. | |||||||||| %{ | The contents of header line(s) in the reply. | |||||||||| %p | The canonical port of the server serving the request. | |||||||||| %{ | The canonical port of the server serving the request, or the server's actual port, or the client's actual port. Valid formats are canonical , local , or remote . | |||||||||| %P | The process ID of the child that serviced the request. | |||||||||| %{ | The process ID or thread ID of the child that serviced the request. Valid formats are pid , tid , and hextid . hextid requires APR 1.2.0 or higher. | |||||||||| %q | The query string (prepended with a ? if a query string exists, otherwise an empty string). | |||||||||| %r | First line of request. | |||||||||| %R | The handler generating the response (if any). | |||||||||| %s | Status. For requests that have been internally redirected, this is the status of the original request. Use %>s for the final status. | |||||||||| %t | Time the request was received, in the format [18/Sep/2011:19:18:28 -0400] . The last number indicates the timezone offset from GMT | |||||||||| %{ | The time, in the form given by format, which should be in an extended strftime(3) format (potentially localized). If the format starts with begin: (default) the time is taken at the beginning of the request processing. If it starts with end: it is the time when the log entry gets written, close to the end of the request processing. In addition to the formats supported by strftime(3) , the following format tokens are supported: strftime(3) formatting in the same format string. You can use multiple %{ tokens instead. | |||||||||| %T | The time taken to serve the request, in seconds. | |||||||||| %u | Remote user if the request was authenticated. May be bogus if return status (%s ) is 401 (unauthorized). | |||||||||| %U | The URL path requested, not including any query string. | |||||||||| %v | The canonical of the server serving the request. | |||||||||| %V | The server name according to the setting. | |||||||||| %X | Connection status when response is completed: | |||||||||| %I | Bytes received, including request and headers. Cannot be zero. You need to enable to use this. | |||||||||| %O | Bytes sent, including headers. Cannot be zero. You need to enable to use this. | |||||||||| %S | Bytes transferred (received and sent), including request and headers, cannot be zero. This is the combination of %I and %O. You need to enable to use this. | |||||||||| %{ | The contents of trailer line(s) in the request sent to the server. | |||||||||| %{ | The contents of trailer line(s) in the response sent from the server. |

Particular items can be restricted to print only for responses with specific HTTP status codes by placing a comma-separated list of status codes immediately following the "%". The status code list may be preceded by a "!

| Format String | Meaning | |---|---| %400,501{User-agent}i | Logs User-agent on 400 errors and 501 errors only. For other status codes, the literal string "-" will be logged. | %!200,304,302{Referer}i | Logs Referer on all requests that do not return one of the three specified codes, "- " otherwise. |

The modifiers "<" and ">" can be used for requests that have been internally redirected to choose whether the original or final (respectively) request should be consulted. By default, the %

look at the original request while all others look at the final request. So for example, %>s

can be used to record the original authenticated user on a request that is internally redirected to an unauthenticated resource.

For security reasons, starting with version 2.0.46, non-printable and other special characters in %r

sequences, where hhhh stands for the hexadecimal representation of the raw byte. Exceptions from this rule are "

, which are escaped by prepending a backslash, and all whitespace characters, which are written in their C-style notation (\n

, etc). In versions prior to 2.0.46, no escaping was performed on these strings so you had to be quite careful when dealing with raw log files.

Since httpd 2.0, unlike 1.3, the %b

format strings do not represent the number of bytes sent to the client, but simply the size in bytes of the HTTP response (which will differ, for instance, if the connection is aborted, or if SSL is used). The %O

will log the actual number of bytes sent over the network.mod_logio

is implemented as a quick-handler and not as a standard handler. Therefore, the mod_cache%R

format string will not return any handler information when content caching is involved.

directive multiple times to build up a time format using the extended format tokens like msec_frac

to store several log entries in memory and write them together to disk, rather than writing them after each request. On some systems, this may result in more efficient disk access and hence higher performance. It may be set only once for the entire server; it cannot be configured per virtual-host.modlogconfig

CustomLog file|pipe format|nickname [env=[!]environment-variable| expr=expression]

The first argument, which specifies the location to which the logs will be written, can take one of the following two types of values:

", followed by the path to a program to receive the log information on its standard input. See the notes on If a program is used, then it will be run as the user who started

. This will be root if the server was started by root; be sure that the program is secure.httpd

When entering a file path on non-Unix platforms, care should be taken to make sure that only forward slashed are used even though the platform may allow the use of back slashes. In general it is a good idea to always use forward slashes throughout the configuration files.

The second argument specifies what will be written to the log file. It can specify either a nickname defined by a previous

directive, or it can be an explicit LogFormatformat string as described in the log formats section.

The third argument is optional and controls whether or not to log a particular request. The condition can be the presence or absence (in the case of a 'env=!

' clause) of a particular variable in the server nameenvironment. Alternatively, the condition can be expressed as arbitrary boolean expression. If the condition is not satisfied, the request will not be logged. References to HTTP headers in the expression will not cause the header names to be added to the Vary header.

modules. For example, if you want to record requests for all GIF images on your server in a separate logfile but not in your main log, you can use:mod_rewrite

SetEnvIf Request_URI \.gif$ gif-image CustomLog gif-requests.log common env=gif-image CustomLog nongif-requests.log common env=!gif-image

Or, to reproduce the behavior of the old RefererIgnore directive, you might use the following:

SetEnvIf Referer example\.com localreferer CustomLog referer.log referer env=!localreferer

directive can take one of two forms. In the first form, where only one argument is specified, this directive sets the log format which will be used by logs specified in subsequent TransferLog

directives. The single argument can specify an explicit format as discussed in the custom log formats section above. Alternatively, it can use a nickname to refer to a log format defined in a previous LogFormat

directives rather than repeating the entire format string. A CustomLogLogFormat

directive that defines a nickname does nothing else -- that is, it only defines the nickname, it doesn't actually apply the format and make it the default. Therefore, it will not affect subsequent

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