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.
Three directives are provided by this module:
The format argument to the
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 |
Remote IP-address | ||||||
%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. | ||||||
%{Foobar}C |
The contents of cookie Foobar in the request sent to the server. | ||||||
%D |
The time taken to serve the request, in microseconds. | ||||||
%{FOOBAR}e |
The contents of the environment variable FOOBAR | ||||||
%f |
Filename | ||||||
%h |
Remote host | ||||||
%H |
The request protocol | ||||||
%{Foobar}i |
The contents of Foobar: header line(s)
in the request sent to the server. | ||||||
%l |
Remote logname (from identd, if supplied). This will return a
dash unless On . | ||||||
%m |
The request method | ||||||
%{Foobar}n |
The contents of note Foobar from another module. | ||||||
%{Foobar}o |
The contents of Foobar: header line(s)
in the reply. | ||||||
%p |
The canonical port of the server serving the request | ||||||
%{format}p |
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. | ||||||
%{format}P |
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 | ||||||
%s |
Status. For requests that got internally redirected, this is
the status of the *original* request --- %>s
for the last. | ||||||
%t |
Time the request was received (standard english format) | ||||||
%{format}t |
The time, in the form given by format, which should be in
strftime(3) format. (potentially localized) | ||||||
%T |
The time taken to serve the request, in seconds. | ||||||
%u |
Remote user (from auth; may be bogus if return status
(%s ) is 401) | ||||||
%U |
The URL path requested, not including any query string. | ||||||
%v |
The canonical | ||||||
%V |
The server name according to the | ||||||
%X |
Connection status when response is completed:
(This directive was | ||||||
%I |
Bytes received, including request and headers, cannot be zero.
You need to enable | ||||||
%O |
Bytes sent, including headers, cannot be zero. You need to
enable |
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
"%". For example, "%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. The status code list may be preceded by a
"!
" to indicate negation:
"%!200,304,302{Referer}i"
logs Referer
on all requests that do not return one of the three
specified codes.
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 %
directives %s, %U, %T,
%D,
and %r
look at the original request
while all others look at the final request. So for example,
%>s
can be used to record the final status of
the request and %<u
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
,
%i
and %o
are escaped using
\xhh
sequences, where hh
stands for the hexadecimal representation of the raw
byte. Exceptions from this rule are "
and
\
, which are escaped by prepending a backslash, and
all whitespace characters, which are written in their C-style
notation (\n
, \t
, 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.
In httpd 2.0, unlike 1.3, the %b
and
%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
format provided by
Some commonly used log format strings are:
"%h %l %u %t \"%r\" %>s %b"
"%v %h %l %u %t \"%r\" %>s %b"
"%h %l %u %t \"%r\" %>s %b \"%{Referer}i\"
\"%{User-agent}i\""
"%{Referer}i -> %U"
"%{User-agent}i"
See the security tips document for details on why your security could be compromised if the directory where logfiles are stored is writable by anyone other than the user that starts the server.
The
The mod_cookies
,
and is deprecated.
The
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.
If a program is used, then it will be run as the user who
started
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
For example, the following two sets of directives have exactly the same effect:
The third argument is optional and controls whether or
not to log a particular request based on the
presence or absence of a particular variable in the server
environment. If the specified environment
variable is set for the request (or is not set, in the case
of a 'env=!name
' clause), then the
request will be logged.
Environment variables can be set on a per-request
basis using the
Or, to reproduce the behavior of the old RefererIgnore directive, you might use the following:
This directive specifies the format of the access log file.
The
The second form of the %
).
This directive has exactly the same arguments and effect as
the