Linux System Administration Recipes A Problem-Solution Approach

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CHAPTER 4 ■ TAKING BACKUPS AND MANAGING DATA12 MESSAGE="/tmp/changemsg.txt"13 echo "Size of files changed in last 24 hrs: $TOTAL bytes" > $MESSAGE14 /usr/bin/mail -s "Filechange on $HOST" "$EMAIL" < $MESSAGE15 rm $MESSAGESave this script as /etc/cron.daily/filechange on each of your machines, and leave it there for aweek or so. You’ll get a daily e-mail from each machine telling you how much change there has been.Line 08 looks for files changed in the past 24 hours (-mtime -x checks for files that have been modified inthe last x × 24 hours); line 09 calls stat to get the size information in bytes. Lines 12–14 handle the mailsending.4-3. Backing Up Your WikiIf you’re using MediaWiki (see recipe 1-4), then your wiki information is kept in a database in MySQL.You should of course be backing up your databases as part of your regular backup strategy (see recipe4-4 for information on backing up MySQL), so from that point of view, your wiki and therefore yourinformation are safe.However, if something goes wrong with your MySQL server or with your Apache server, you maytemporarily not be able to get at the wiki, which is not much good if it contains your notes on how toresolve problems with MySQL and/or Apache! So, it’s a good idea to also have a static mirror.■ Note If you’re using a text-based wiki (for example, moinmoin) rather than a database-based one, this is less ofa problem, because you can access the files manually and read them with a text editor if need be. However, it’sprobably still a good idea to have a copy of the wiki files on a second machine (other than your web server),created either with httrack as described here or with a cronjob and cp.A good tool for this is httrack, which is a website-mirroring tool. (It’s available as the httrackpackage for Debian/Ubuntu or from http://www.httrack.com.)For a standard MediaWiki install living at http://wiki.example.com, this is the command to runfrom the command line:httrack "http://wiki.example.com/" -O "/home/jkemp/wikibackup" \"+*.example.com/*" "-*oldid*" -vTo run an update daily, edit your crontab with crontab -e, and add a line that looks like this:5 4 * * * httrack –update "http://wiki.example.com/" -O "/home/jkemp/wikibackup" "+*.example.com/*" "-*oldid*"100Download at WoweBook.Com
CHAPTER 4 ■ TAKING BACKUPS AND MANAGING DATA■ Note Alternatively, you can create a two-line script:#!/bin/bash/usr/bin/httrack "http://wiki.example.com/" .-O "/home/jkemp/wikibackup" "+*.example.com/*" "-*oldid*" -vand save it as /etc/cron.daily/wikimirror. Note that in Debian/Ubuntu, run-parts (which handles/etc/cron.*/ files) will not run any file that has any extension, so don’t call this wikimirror.sh!The first command will store a copy of the wiki at /home/jkemp/wikibackup/ (the -O output option).The -v option at the end means verbose; you may want to remove this once you’ve run the command tocheck that it works. The cron entry runs an update daily at 4:05 a.m.; the --update option means thathttrack won’t ask whether it’s OK to overwrite your existing mirror.The +*.example.com/* and -*oldid* options are filters. The first one limits the mirror to pageswithin the example.com domain, ensuring that any links to external pages won’t be mirrored. (That iswhat you want; if you need those pages, you can get them from the external sites!) +regexp means thatthe backup should include only the links that match this regexp.The -*oldid* part is MediaWiki-specific; if you’re using another wiki, check what convention it usesfor its history pages. MediaWiki keeps a history of all the changes to a page. This is great, but if youmirror every single version of a page, it’s going to take a long time and take up a lot of space. Remember,this mirror doesn’t need to be a full backup of your wiki. The standard backup of your database back endtakes care of that. This is just for emergency reference. History pages and links to a diff between the oldversion and the current one in MediaWiki are referred to in the following format:http://wiki.example.com/index.php?title=Main_Page&oldid=5253http://wiki.example.com/index.php?title=Main_Page&diff=5249&oldid=5238So, by using the -regexp notation, which means “exclude links that match this regexp,” you excludeall the history records.■ Note If you have a link to an external page with information about what to do when your Internet accessbreaks, you may want to copy that information onto your wiki and add a note about where it came from. Or, keepthe bookmark on your phone or other data device.Once you’ve run this command, looked at the mirror produced at /home/jkemp/wikibackup/, and confirmed that it has done what you want, you can add it to your crontab.101Download at WoweBook.Com
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Contents■About the Author .......
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■ CONTENTS3-7. Writing a Nagios P
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■ CONTENTS■Chapter 8: Using the
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■ CONTENTSAbout the Author■Juli
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■ CONTENTSAcknowledgmentsMany tha
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■ CONTENTSIntroductionThis book i
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■ INTRODUCTIONDownloading the Cod
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C H A P T E R 1■ ■ ■Saving Yo
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CHAPTER 1 ■ SAVING YOURSELF EFFOR
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C H A P T E R 2■ ■ ■Centraliz
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CHAPTER 2 ■ CENTRALIZING YOUR NET
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Page 69 and 70: CHAPTER 2 ■ CENTRALIZING YOUR NET
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CHAPTER 6 ■ SECURING YOUR SYSTEMS
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C H A P T E R 7■ ■ ■Working w
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CHAPTER 7 ■ WORKING WITH APACHEOn
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CHAPTER 7 ■ WORKING WITH APACHEdi
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CHAPTER 7 ■ WORKING WITH APACHE4.
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CHAPTER 7 ■ WORKING WITH APACHE
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CHAPTER 7 ■ WORKING WITH APACHEAl
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CHAPTER 7 ■ WORKING WITH APACHE
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C H A P T E R 8■ ■ ■Making Be
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CHAPTER 8 ■ USING THE COMMAND LIN
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C H A P T E R 9■ ■ ■Working w
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CHAPTER 9 ■ WORKING WITH TEXT IN
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C H A P T E R 10■ ■ ■Things G
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CHAPTER 10 ■ THINGS GO IN, THINGS
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C H A P T E R 11■ ■ ■Tracking
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CHAPTER 11 ■ TRACKING DOWN BUGSTh
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CHAPTER 11 ■ TRACKING DOWN BUGS01
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CHAPTER 11 ■ TRACKING DOWN BUGS
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CHAPTER 11 ■ TRACKING DOWN BUGSTh
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CHAPTER 11 ■ TRACKING DOWN BUGSAn
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CHAPTER 11 ■ TRACKING DOWN BUGS#
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C H A P T E R 12■ ■ ■Managing
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CHAPTER 12 ■ MANAGING TIME AND PE
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APPENDIX■ ■ ■Perl TipsSee rec
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APPENDIX ■ PERL TIPS• Date::Par
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APPENDIX ■ PERL TIPSPerl Syntax N
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■ ■ ■Index■Symbols$CDPATH,
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■ INDEXenscript option (printing)
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■ INDEX■NNagiosadding hosts to,
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■ INDEXsyslogcentralized logging
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