NAME¶
Log::Agent::Driver::File - file logging driver for Log::Agent
SYNOPSIS¶
use Log::Agent;
require Log::Agent::Driver::File;
my $driver = Log::Agent::Driver::File->make(
-prefix => "prefix",
-duperr => 1,
-stampfmt => "own",
-showpid => 1,
-magic_open => 0,
-channels => {
error => '/tmp/output.err',
output => 'log.out',
debug => '../appli.debug',
},
-chanperm => {
error => 0777,
output => 0666,
debug => 0644
}
);
logconfig(-driver => $driver);
DESCRIPTION¶
The file logging driver redirects
logxxx() operations to specified files,
one per channel usually (but channels may go to the same file).
The creation routine
make() takes the following arguments:
- "-channels" => hash ref
- Specifies where channels go. The supplied hash maps channel names
("error", "output" and "debug") to
filenames. When "-magic_open" is set to true, filenames are
allowed magic processing via perl's open(), so this allows things
like:
-channels => {
'error' => '>&FILE',
'output' => '>newlog', # recreate each time, don't append
'debug' => '|mailx -s whatever user',
}
If a channel (e.g. 'output') is not specified, it will go to the 'error'
channel, and if that one is not specified either, it will go to STDERR
instead.
If you have installed the additional "Log::Agent::Rotate" module,
it is also possible to override any default rotating policy setup via the
"-rotate" argument: instead of supplying the channel as a single
string, use an array reference where the first item is the channel file,
and the second one is the "Log::Agent::Rotate" configuration:
my $rotate = Log::Agent::Rotate->make(
-backlog => 7,
-unzipped => 2,
-max_write => 100_000,
-is_alone => 1,
);
my $driver = Log::Agent::Driver::File->make(
...
-channels => {
'error' => ['errors', $rotate],
'output' => ['output, $rotate],
'debug' => ['>&FILE, $rotate], # WRONG
},
-magic_open => 1,
...
);
In the above example, the rotation policy for the "debug" channel
will not be activated, since the channel is opened via a magic
method. See Log::Agent::Rotate for more details.
- "-chanperm" => hash ref
- Specifies the file permissions for the channels specified by
"-channels". The arguemtn is a hash ref, indexed by channel
name, with numeric values. This option is only necessary to override the
default permissions used by Log::Agent::Channel::File. It is generally
better to leave these permissive and rely on the user's umask. See
"umask" in perlfunc(3) for more details..
- "-duperr" => flag
- When true, all messages normally sent to the "error" channel are
also copied to the "output" channel with a prefixing made to
clearly mark them as such: "FATAL: " for logdie(),
logcroak() and logconfess(), "ERROR: " for
logerr() and "WARNING: " for logwarn().
Note that the "duplicate" is the original error string for
logconfess() and logcroak(), and is not strictly identical
to the message that will be logged to the "error" channel. This
is a an accidental feature.
Default is false.
- "-file" => file
- This switch supersedes both "-duperr" and "-channels"
by defining a single file for all the channels.
- "-perm" => perm
- This switch supersedes "-chanperm" by defining consistent for
all the channels.
- "-magic_open" => flag
- When true, channel filenames beginning with '>' or '|' are opened using
Perl's open(). Otherwise, sysopen() is used, in append mode.
Default is false.
- "-prefix" => prefix
- The application prefix string to prepend to messages.
- "-rotate" => object
- This sets a default logfile rotation policy. You need to install the
additional "Log::Agent::Rotate" module to use this switch.
object is the "Log::Agent::Rotate" instance describing the
default policy for all the channels. Only files which are not opened via a
so-called magic open can be rotated.
- "-showpid" => flag
- If set to true, the PID of the process will be appended within square
brackets after the prefix, to all messages.
Default is false.
- "-stampfmt" => (name | CODE)
- Specifies the time stamp format to use. By default, my "own"
format is used. The following formats are available:
date "[Fri Oct 22 16:23:10 1999]"
none
own "99/10/22 16:23:10"
syslog "Oct 22 16:23:10".
You may also specify a CODE ref: that routine will be called every time we
need to compute a time stamp. It should not expect any parameter, and
should return a string.
CHANNELS¶
All the channels go to the specified files. If a channel is not configured, it
is redirected to 'error', or STDERR if no 'error' channel was configured
either.
Two channels not opened via a
magic open and whose logfile name is the
same are effectively
shared, i.e. the same file descriptor is used for
both of them. If you supply distinct rotation policies (e.g. by having a
default policy, and supplying another policy to one of the channel only), then
the final rotation policy will depend on which one was opened first. So don't
do that.
CAVEAT¶
Beware of
chdir(). If your program uses
chdir(), you should always
specify logfiles by using absolute paths, otherwise you run the risk of having
your relative paths become invalid: there is no anchoring done at the time you
specify them. This is especially true when configured for rotation, since the
logfiles are recreated as needed and you might end up with many logfiles
scattered throughout all the directories you
chdir()ed to.
Logging channels with the same pathname are shared, i.e. they are only opened
once by "Log::Agent::Driver::File". Therefore, if you specify
different rotation policy to such channels, the channel opening order will
determine which of the policies will be used for all such shared channels.
Such errors are flagged at runtime with the following message:
Rotation for 'logfile' may be wrong (shared with distinct policies)
emitted in the logs upon subsequent sharing.
AUTHORS¶
Originally written by Raphael Manfredi <Raphael_Manfredi@pobox.com>,
currently maintained by Mark Rogaski <mrogaski@cpan.org>.
Thanks to Joseph Pepin for suggesting the file permissions arguments to
make().
LICENSE¶
Copyright (C) 1999 Raphael Manfredi. Copyright (C) 2002 Mark Rogaski; all rights
reserved.
See
Log::Agent(3) or the README file included with the distribution for
license information.
SEE ALSO¶
Log::Agent::Driver(3),
Log::Agent(3),
Log::Agent::
Rotate(3).