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    Using tar scripts and CRON to back up

    There are three bash shell scripts listed below.
    They can be run manually or be added to a cron script as appropriate:
    backup_all.bsh can be put in the weekly cron
    backup_inc.bsh can be put into the daily cron
    restor_all.bsh is run manually when ever needed

    How to setup cron scripts is shown below the backup and restore scripts.

    The list of directories to back up or restore are in both backup scripts and should be identical. Modify them to suit your needs. They should not include the destination for the tar file which is created.
    "bkupdir" is the full path to the directory where the tar files that are created are stored. The directory should not be among those backed up.
    "bkupname" is the name that will be given to the file. Change the string portion to suit yourself.

    Consult the tar man for details on tar parameters and auxiliary files.

    backup_all.bsh
    ***************
    Code:
    #!/bin/bash
    #copyright 2004 Jerry L Kreps
    #released under the terms of the GNU General Public License
    bkupdir=/backup
    bkupname="Webserver_fullbkup_"$(date +'%Y-%m-%d')
    tar --create
    --gzip
    --sparse
    --same-permissions
    --file=$bkupdir/$bkupname.tgz
    --blocking-factor=256
    --directory=/
    --label=$bkupname
    /boot /etc /home /lib /misc /opt /root /sbin /selinux /usr /var 2> $bkupdir/backup_errors.txt &

    backup_inc.bsh
    ************************
    Code:
    #!/bin/bash
    #copyright 2004 Jerry L Kreps
    #released under the terms of the GNU General Public License
    bkupdir=/backup
    bkupname="Webserver_incbkup_"$(date +'%Y-%m-%d')
    tar --create
    --gzip
    --sparse
    --same-permissions
    --file=$bkupdir/$bkupname.tgz
    --blocking-factor=256
    --directory=/
    --label=$bkupname
    --listed-incremental=$bkupdir/webserver.snar
    /bin /boot /etc /home /lib /misc /opt /root /sbin /selinux /usr /var &


    "restore_all.bsh" is followed by the tar file which will be extracted as the first parameter.

    restore_all.bsh
    *********************
    Code:
    #!/bin/bash
    #copyright 2004 Jerry L Kreps
    #released under the terms of the GNU General Public License
    tar -xzsSpf --numeric-owner %1 2> /backup/restore_errors.txt



    Newbie: Intro to cron
    Date: 30-Dec-99
    Author: cogNiTioN <cognition@attrition.org>

    Cron

    This file is an introduction to cron, it covers the basics of what cron does,
    and how to use it.

    What is cron? ( Consult the man on cron and crontab for more details)

    Cron is the name of program that enables unix users to execute commands or
    scripts (groups of commands) automatically at a specified time/date.

    Cron is a daemon, which means that it only needs to be started once, and will
    lay dormant until it is required. The cron daemon, or crond, stays dormant
    until a time specified in one of the config files, or crontabs.

    On most Linux distributions crond is automatically installed and entered into
    the start up scripts. To find out if it's running do the following:

    cog@pingu $ ps aux | grep crond
    root 311 0.0 0.7 1284 112 ? S Dec24 0:00 crond

    The second line shows that crond is running.

    If it's not running then
    sudo /etc/init.d/cron start

    Using cron

    There are a few different ways to use cron (surprise, surprise).

    In the /etc directory you will probably find some sub directories called
    'cron.hourly', 'cron.daily', 'cron.weekly' and 'cron.monthly'. If you place
    a script into one of those directories it will be run either hourly, daily,
    weekly or monthly, depending on the name of the directory.

    If you want more flexibility than this, you can edit a crontab (the name
    for cron's config files). The main config file is normally /etc/crontab.


    jerry@jerry-sonylaptop:~$ cat /etc/crontab
    Code:
    # /etc/crontab: system-wide crontab    
    # Unlike any other crontab you don't have to run the `crontab'
    # command to install the new version when you edit this file
    # and files in /etc/cron.d. These files also have username fields,
    # that none of the other crontabs do.
    
    SHELL=/bin/sh
    PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
    
    # m h dom mon dow user command
    17 *  * * *  root  cd / && run-parts --report /etc/cron.hourly
    25 6  * * *  root  test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )
    47 6  * * 7  root  test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly )
    52 6  1 * *  root  test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )
    #
    The first part is almost self explanatory; it sets the variables for cron.

    SHELL is the 'shell' cron runs under. If unspecified, it will default to
    the entry in the /etc/passwd file.

    PATH contains the directories which will be in the search path for cron
    e.g if you've got a program 'foo' in the directory /usr/cog/bin, it might
    be worth adding /usr/cog/bin to the path, as it will stop you having to use
    the full path to 'foo' every time you want to call it.


    Here is part of /etc/crontab edited to show it executing backup_all.bsh every Sunday morning at 1AAM
    and doing the incremental backups at 1AM every Mon thru Fri morning. /backup is an NFS mount to a second HD or remote server.
    Code:
    00 1 * * 7  root /backup/backup_all.bsh
    00 1 * * 1-5 root /backup/backup_inc.bsh
    17 *  * * *  root  cd / && run-parts --report /etc/cron.hourly
    25 6  * * *  root  test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )
    47 6  * * 7  root  test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly )
    52 6  1 * *  root  test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )


    Now for the more complicated second part of a crontab file.
    An entry in cron is made up of a series of fields, much like the /etc/passwd
    file is, but in the crontab they are separated by a space. There are normally
    seven fields in one entry. The fields are:

    m h dom mon dow user cmd

    m = minute This controls what minute of the hour the command will run on,
    and is between '0' and '59'
    h = hour This controls what hour the command will run on, and is specified in
    the 24 hour clock, values must be between 0 and 23 (0 is midnight)
    dom This is the Day of Month, that you want the command run on, e.g. to
    run a command on the 19th of each month, the dom would be 19.
    mon This is the month a specified command will run on, it may be specified
    numerically (0-12), or as the name of the month (e.g. May)
    dow This is the Day of Week that you want a command to be run on, it can
    also be numeric (0-7) or as the name of the day (e.g. sun).
    user This is the user who runs the command.
    cmd This is the command that you want run. This field may contain
    multiple words or spaces.

    If you don't wish to specify a value for a field, just place a * in the
    field.

    e.g.
    01 * * * * root echo "This command is run at one min past every hour"
    17 8 * * * root echo "This command is run daily at 8:17 am"
    17 20 * * * root echo "This command is run daily at 8:17 pm"
    00 4 * * 0 root echo "This command is run at 4 am every Sunday"
    * 4 * * Sun root echo "So is this"
    42 4 1 * * root echo "This command is run 4:42 am every 1st of the month"
    01 * 19 07 * root echo "This command is run hourly on the 19th of July"

    Notes:

    Under dow 0 and 7 are both Sunday.

    If both the dom and dow are specified, the command will be executed when
    either of the events happen.
    e.g.
    * 12 16 * Mon root cmd
    Will run cmd at midday every Monday and every 16th, and will produce the
    same result as both of these entries put together would:
    * 12 16 * * root cmd
    * 12 * * Mon root cmd

    Vixie Cron also accepts lists in the fields. Lists can be in the form, 1,2,3
    (meaning 1 and 2 and 3) or 1-3 (also meaning 1 and 2 and 3).
    e.g.
    59 11 * * 1,2,3,4,5 root backup.sh
    Will run backup.sh at 11:59 Monday, Tuesday, Wednesday, Thursday and Friday,
    as will:
    59 11 * * 1-5 root backup.sh

    Cron also supports 'step' values.
    A value of */2 in the dom field would mean the command runs every two days
    and likewise, */5 in the hours field would mean the command runs every
    5 hours.
    e.g.
    * 12 10-16/2 * * root backup.sh
    is the same as:
    * 12 10,12,14,16 * * root backup.sh

    */15 9-17 * * * root connection.test
    Will run connection.test every 15 mins between the hours or 9am and 5pm

    Lists can also be combined with each other, or with steps:
    * 12 1-15,17,20-25 * * root cmd
    Will run cmd every midday between the 1st and the 15th as well as the 20th
    and 25th (inclusive) and also on the 17th of every month.
    * 12 10-16/2 * * root backup.sh
    is the same as:
    * 12 10,12,14,16 * * root backup.sh

    When using the names of weekdays or months, it isn't case sensitive, but only
    the first three letters should be used, e.g. Mon, sun or Mar, jul.

    Comments are allowed in crontabs, but they must be preceded with a '#', and
    must be on a line by them self.
    ....

    Additional Reference:
    Man pages: cron(8) crontab(5) crontab(1)
    Book: _Running Linux_ (O'Reilly ISBN: 1-56592-469-X)
    © Copyright 2000 cogNiTioN <cognition@attrition.org>

    "A nation that is afraid to let its people judge the truth and falsehood in an open market is a nation that is afraid of its people.”
    – John F. Kennedy, February 26, 1962.
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