|
cronolog FAQ
The questions here are compiled from a review of the emails regarding
cronolog that I have received over the years. If you have a question
that you think should be included here please email me.
Andrew Ford
2002-11-11
What is cronolog?
cronolog is a simple program that reads log messages from its
input and writes them to a set of output files, the names of which are
constructed using a template and the current date and time. cronolog is
intended to be used in conjunction with a Web server, such as Apache,
to split the access log into separate log files by day, month or other
specified period.
The template uses the same format specifiers as the Unix date command
(which are the same as the standard C strftime library function).
Each character in the template represents a character in the expanded
filename, except for date and time format specifiers, which are
replaced by their expansion. Format specifiers consist of a `%'
followed by one of the following characters listed in the usage page.
Take for example the following Apache configuration directives:
CustomLog "|/usr/sbin/cronolog /web/logs/%Y/%m/%d/access.log"
ErrorLog "|/usr/sbin/cronolog /web/logs/%Y/%m/%d/errors.log"
These would instruct Apache to pipe its access and error log messages
into separate copies of cronolog, which would create new log files
each day in a directory hierarchy structured by date, i.e. on 31
December 1996 messages would be written to
/web/logs/1996/12/31/access.log
/web/logs/1996/12/31/errors.log
after midnight it would use the files
/web/logs/1997/01/01/access.log
/web/logs/1997/01/01/errors.log
The directories 1997, 1997/01 and
1997/01/01 would be created if they did not already exist.
How should I organize my log files?
That is really up to you, however I like to include the year (four
digits) and month (as a decimal number) in the filenames and store the
files in separate directories by year. The filename templates I use
are:
/web/xxx/logs/%Y/%Y-%m-xxx-access.log
/web/xxx/logs/%Y/%Y-%m-xxx-errors.log
where xxx is an abbreviation for the name of the web site.
With this scheme there will be a maximum of 24 files in each
bottom-level directory, and the filenames are self-explanatory and can
also be sorted chronologically.
I would like to roll over my logs daily but not at midnight
Use the --delay option to delay the start of each period by
the specified delay, which can be specified as 12 hours,
15 minutes (or 15 mins). For example to roll over
logs daily at mid-day, you could specify:
CustomLog "|/usr/sbin/cronolog --delay '12 hours' /web/logs/%Y/%m/%d/access.log"
Note that the delay specifier must be quoted if it contains spaces and
must use different quote characters to those used to quote the entire
command as an argument to the Apache directive.
How do I generate the name of yesterday's log file
Use the GNU date command. It can format arbitrary dates and
can interprete dates specified as "yesterday" or "2 days
ago", or even "12:00 3 weeks 1 day ago" for if you rotate
logs hourly. It takes the same date and time specifiers as cronolog,
so if you want to find out the name of yesterday's log file you
could specify something like:
date --date "yesterday" +"%Y-%m-%d-access.log"
Could cronolog be extended to compress or delete old log files?
There are problems with doing such things from cronolog. You might
have multiple cronolog processes writing to the same file and it is a
matter of chance which process gets to compress or delete the files.
It is better to run periodic programs from cron (on Unix and
Unix-like systems).
See the previous answer for how to generate filenames from templates for specific dates.
Is cronolog available as an Apache module?
A beta version of the module is written, but it has not received much
testing. (further details)
Does cronolog run on Windows?
Yes. Klaus Mueller kindly provided Win32 binaries for
cronolog version 1.6.1.
Why do I have problems compiling cronolog on BSD Unix?
Compiling cronolog on BSD systems gives the following compilation
error or something very similar:
gcc -DPACKAGE=\"cronolog\" -DVERSION=\"1.6.1\" -DSTDC_HEADERS=1
-DTIME_WITH_SYS_
TIME=1 -DHAVE_TM_ZONE=1 -DHAVE_FCNTL_H=1 -DHAVE_LIMITS_H=1 -DHAVE_UNISTD_H=1
-DH
AVE_STRFTIME=1 -DHAVE_VPRINTF=1 -DHAVE_MKDIR=1 -DHAVE_MKTIME=1
-DHAVE_PUTENV=1 -
DHAVE_STRPTIME=1 -DHAVE_LOCALTIME_R=1 -I. -I. -I../lib -g -O2 -c
cronoutils.c
cronoutils.c:74: `timezone' redeclared as different kind of symbol
/usr/include/time.h:144: previous declaration of `timezone'
*** Error code 1
The offending line looks like:
extern long int timezone;
The solution is to delete or comment out this line from
cronoutils.c. I have removed it in cronolog 1.6.2 as it
doesn't seem to be needed any more even on Linux.
|
