265 lines
10 KiB
Markdown
265 lines
10 KiB
Markdown
# Using Logwatch to monitor Cloudflare DDNS updater script <!-- omit in toc -->
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The Cloudflare DDNS update script's log file has been set up so that utilities
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like Logwatch can easily parse it. In order to make that happen, a LogFile
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Group file, Service and Script have to be created for Logwatch to generate
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reports. The correct (general) directory structure has been created in this git
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archive already. Below are the details of each file.
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## Contents <!-- omit in toc -->
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- [LogFile Group file (/etc/logwatch/conf/logfiles/cfddns.conf)](#logfile-group-file-etclogwatchconflogfilescfddnsconf)
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- [Log file location](#log-file-location)
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- [Archive location and name format](#archive-location-and-name-format)
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- [External script for timestamp processing](#external-script-for-timestamp-processing)
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- [Service definition file (/etc/logwatch/conf/services/cfddns.conf)](#service-definition-file-etclogwatchconfservicescfddnsconf)
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- [LogFile Group file definition](#logfile-group-file-definition)
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- [Report title](#report-title)
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- [Service script (/etc/logwatch/scripts/services/cfddns)](#service-script-etclogwatchscriptsservicescfddns)
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- [Detail levels](#detail-levels)
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- [Timestamp processing script (/etc/logwatch/scripts/shared/sqfullstampanywhere)](#timestamp-processing-script-etclogwatchscriptssharedsqfullstampanywhere)
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- [The time format specification](#the-time-format-specification)
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- [The search REGEX](#the-search-regex)
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- [Testing](#testing)
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- [Final thoughts](#final-thoughts)
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## LogFile Group file (/etc/logwatch/conf/logfiles/cfddns.conf)
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### Log file location
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Update this as needed to point to the location and name of the log file
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generated by the updater script. Remember, by default, the log file is created
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in the same directory as the script itself.
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```Ini
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LogFile = /path/to/your/cfddns.log
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...
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```
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Best practices suggest you use the *-l*
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flag to change this location to something like */var/log/cfddns.log*, for
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example. In that case, the entry would look like:
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```Ini
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LogFile = /var/log/cfddns.log
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...
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```
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### Archive location and name format
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If you want Logwatch to process old (archived) log files generated by something
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like *Logrotate*, then you have to specify the location and file name format of
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those files. I've included the generalized compressed format of such rotated
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files as the default in the script. Suppose you store your log files in the
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recommended location (*/var/log/*) and are using *Logrotate* with compression
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enabled, the archive line would look like:
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```Ini
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...
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Archive = /var/log/cfddns.log.?.gz
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...
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```
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This would tell Logwatch, when the archive option is set to true, that your
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*cfddns.log* files are archived as: *cfddns.log.1.gz*, *cfddns.log.2.gz*, etc.
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and are all located in */var/log/*.
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**Note: This line is totally optional and only used if you set the archive
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option in Logwatch to true. You can comment/delete this line if you wish.**
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### External script for timestamp processing
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Since the log file uses a non-standard (according to Logwatch) method of
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datestamping, a custom filter had to be created. See the
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[relevant](#timestamp-processing-script-etclogwatchscriptssharedsqfullstampanywhere)
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section of this document for more information.
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The script file is called with an *\** before the filename.
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```Ini
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...
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*sqFullStampAnywhere
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...
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```
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If you change the name of this file, you will have to change this line.
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Remember that whatever you type here as a name is converted to all-lowercase
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so your filename should be all lowercase also.
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## Service definition file (/etc/logwatch/conf/services/cfddns.conf)
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### LogFile Group file definition
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The service file needs to know what group of log files it is responsible for
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processing. This MUST match the name of your *LogFile Group file*:
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```Ini
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LogFile = cfddns
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...
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```
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If you change your LogFile Group filename, then update it here too without the
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*.conf* extension.
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### Report title
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The Logwatch output file (html or text) is divided into sections. You can
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define the title to be anything that has meaning for you. I have arbitrarily
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chosen *"CloudFlare DDNS update"* but you can change it to anything you want by
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modifying the line:
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```Ini
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...
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Title = "CloudFlare DDNS update"
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```
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## Service script (/etc/logwatch/scripts/services/cfddns)
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Logwatch calls any script with a name that **matches the service name**. You'll
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notice that I just named everything *cfddns* to keep things simple. You can
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change this to whatever you want, however. If you changed the service name to
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*"cloudflare*.conf", for example, you would have to rename this script file to
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"*cloudflare*" with no extension. Note: The script is a PERL file (note the
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shebang) but it can be written in any language.
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In essence, Logwatch just spits out the log file(s) defined in the LogFile Group
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file as standard input (STDIN) for the script and then takes whatever is output
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(STDOUT) from the script to assemble into it's report.
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### Detail levels
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The script supports four (4) detail levels as follows:
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- **Level 0: Summary output only**
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- This will display an aggregate total of certain logged elements. It will
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display the total number of hostnames (A and AAAA) that are already
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up-to-date, those that needed updating, those successfully updated and the
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total number of errors (of any type) encountered by the script. All totals
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are relative to the reporting period Logwatch is using (--range parameter).
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**This is the recommended reporting level.** It does not take up much space
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and is quick to read. If you see successful updates match the number of
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needed updates and no errors logged, then things are working properly. If
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you notice errors, you should consult the full logs.
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- **Levels 1-4: Critical messages**
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- This uses the data which is summarized by Level 0 but outputs the actual
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messages in the log file. For example, you will see the actual text of the
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errors logged instead of just a total number of errors. This level of
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reporting is useful when *initially* monitoring the script's operation since
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you can see the actual text of any generated errors.
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- **Level 5: Verbose (debugging) output**
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- Like the previous level, this outputs the actual messages found in the log
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file. However, it also includes *[INFO] tags* which contain logged messages
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such as the detected IP address and the specific names of any hostnames not
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found in your Cloudflare account, etc. This level of reporting is useful in
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diagnosing why errors are occurring or if you just want more insight into
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how the script works.
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**This level of output will make your Logwatch reports longer and consume
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more of your time to review. You should not use this level day-to-day.**
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- **Levels 6+: Complete log file dump**
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- Any number greater than 5 passed as a detail level will trigger the script
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to dump the entire log file out to Logwatch line-by-line. This is useful
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only if you are debugging an issue and cannot get access to the actual raw
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log file itself. The actual log file is colour-coded which makes it much
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easier to read for debugging purposes.
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**Use this detail level only when you need to see the entire log file and
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cannot otherwise access the log file.**
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## Timestamp processing script (/etc/logwatch/scripts/shared/sqfullstampanywhere)
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This is basically a modified version of the '*applyeurodate*' script that comes
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with Logwatch. It had to be modified to search within [square brackets] and to
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accept characters coming before the stamp (i.e. ANSI colour codes). If you
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change the '**stamp**' variable in the updater script to update the timestamp to
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your liking (which to totally fine!) then you'll probably have to update this
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file. There are two lines you need to modify to suit your new '**stamp**'
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variable.
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### The time format specification
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'*$SearchDate*' is the variable used in the PERL script to do exactly what it
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says, search for the date stamp. I have it set up to look for the format
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'*year-month-date hour:minute:second*'. Note, we don't care about brackets or
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anything here, we're just defining the format of the date/time stamp.
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```Perl
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...
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$SearchDate = TimeFilter('%Y-%m-%d %H:%M:%S');
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...
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```
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If you changed the '**stamp**' variable so it was formatted as '*month/day/year
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hour:minute*' (ex: '*[09/27/2018 18:38]*') then you'd update the **$SearchDate**
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variable as follows (note: no mention of the square brackets!):
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```Perl
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...
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$SearchDate = TimeFilter('%m/%d/%Y %H:%M');
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...
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```
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### The search REGEX
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The PERL script uses a '*regular expression*' (REGEX) to search within the log file for
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'*$SearchDate*'. For the default datestamp, this specification looks like:
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```Perl
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...
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if ($ThisLine =~ m/\[$SearchDate\] /o) {
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...
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```
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The REGEX appears between '*m/*' and '*/o*'. In this case, it searches for
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'*$SearchDate*' inside [square brackets] appearing anywhere on the line. This
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is because ANSI colour-codes often appear before the datestamp in the default
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log file. If you have modified this so that your datestamp appears at the
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beginning of the line and in the example format in the section above (using
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slashes instead of dashes) then you'd rewrite this REGEX as follows:
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```Perl
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...
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if ($ThisLine =~ m/^\[$SearchDate\] /o) {
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...
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```
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or using regular brackets anywhere on the line:
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```Perl
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...
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if ($ThisLine =~ m/\($SearchDate\) /o) {
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...
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```
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or without any brackets but appearing at the beginning of the line:
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```Perl
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...
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if ($ThisLine =~ m/^$SearchDate /o) {
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...
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```
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## Testing
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Run *logwatch --help* and note the options. You can test just this service
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locally on your screen with the following command (assuming you kept default
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names for everything):
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```Bash
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# Summary output, entire duration of log file
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logwatch --service cfddns --output stdout --format text --range all --detail 0
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# Minimal detail, yesterday only
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logwatch --service cfddns --output stdout --format text --range yesterday --detail 3
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# Verbose output, today only
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logwatch --service cfddns --output stdout --format text --range today --detail 5
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```
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## Final thoughts
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That's it! I'm a horrible PERL programmer so if anyone can optimize/improve the
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script file used for Logwatch then please do it! Otherwise, I hope this made
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sense and helped you integrate the updater script with Logwatch for easy
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monitoring :-) |