Smart Backup Script Post: 302467864

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Top Forums Shell Programming and Scripting Smart Backup Script Post 302467864 by agama on Sunday 31st of October 2010 07:32:51 PM

10-31-2010

Registered User

A couple of things come to mind looking at your examples.

First, the -S option sorts by size; you'll not be removing the oldest first, but the largest which is likely the most recent, and probably not what you want.

Secondly, I'd switch to the directory that has your backup files in it and use a dot (.) on the df command; this ensures that you are checking the correct device while still allowing it to be variable.

This is the way that I would go about it -- needs only one df and one ls call which will be more efficient:

Code:

#!/usr/bin/env ksh

backup_dir=${1:-foo}
if ! cd $backup_dir
then
        echo "cannot switch to backup directory: $backup_directory"
        exit 1
fi
(
        df -B 1 . | tail -1
        ls -rlt *.tgz
) | awk -v need_free=${2:-20} '
        BEGIN {
                need_free *= 1024 ** 3;         # assume 20 on cmd line for 20GiB
        }
        NR == 1 {                               # output from df; adjust need based on available
                need_free -= $4;
                next;
        }

        NF < 5 { next; }                # don't catch total from ls

        {
                if( need_free <= 0 )    # if desired free space reached
                        exit( 0 );
                print $NF;               # no, add this file to the list
                need_free -= $5;     # dec free space needed
        }
'| xargs rm

This is just a basic example. With anything that deletes files I always like to have a 'no-exec' mode that lists what it might do until I'm comfortable that it works right. In any case, you might want to add something that limits the max number of files that it can delete or somesuch that prevents deleting all of the backup files.

The -B option on the df command causes it to list values in bytes; makes it easier. The -rlt option to ls lists files by time, showing size and in reverse order so that the oldest file (by modification time) is listed first. Both the ls and df commands are executed in a subshell so that the output can easily be pushed into the awk that does the real work.

Hope this is useful

agama

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LEARN ABOUT MOJAVE

nisbackup

nisbackup(1M)						  System Administration Commands					     nisbackup(1M)

NAME

       nisbackup - backup NIS+ directories

SYNOPSIS

       nisbackup [-v] backup-dir directory...

       nisbackup [-v] -a backup-dir

DESCRIPTION

       nisbackup  backs  up a NIS+ directory object on a NIS+ master server. Updates to the NIS+ database will be temporarily disabled while  nis-
       backup is running.  The	backup-dir is a UNIX directory that must exist prior to running  nisbackup. The  nisbackup command can be used	to
       backup  an  individual  NIS+  directory	object	or  all ( -a) of the NIS+ directory objects served by a master server.	The NIS+ directory
       objects being backed up will be placed into subdirectories under the  backup-dir directory.  These subdirectories are  named  according	to
       the  NIS+  directory  object  they contain.  nisbackup operates on individual NIS+ directory objects  (for example,  org_dir.wiz.com). This
       allows an administrator to selectively backup specific directories.

       The  rpc.nisd(1M) process must be running on the master server with a stable NIS+ database for  nisbackup to complete. nisbackup  will  not
       attempt	to  correct any corruption in the NIS+ database, so it is important that backups be done regularly as part of the NIS+ administra-
       tion.

       The first synopsis is used to backup a single NIS+ directory object or a list of NIS+ directory objects. The objects can be partially qual-
       ified or fully qualified. The machine on which the command is executing must be the master for the NIS+ directory objects specified.

       The  second synopsis will backup all of the NIS+ directory objects that are served by this master. The  -a option is the recommended method
       of backing up a master server,  since it will backup all NIS+ directory objects that are served by  this master. If this server is a master
       server for more than one domain, the backup will include NIS+ directories that belong to all of the domains served.  Individual NIS+ direc-
       tory objects can be selected for restoring from a  backup-dir created with the  -a option. See  nisrestore(1M).

       The  -a option only includes directory objects for which this server is the master. It is possible, but not  recommended,  to  configure  a
       master  server as a replica for other domains. The objects belonging to those replicated domains will not be backed up with the	-a option.
       The backup of replicated objects must be run on the master server for those objects.

       Do not use the same  backup-dir to backup different master servers. Each master server must have its own  backup-dir.

       nisbackup will set the  rpc.nisd(1M) to read only mode, which will disable updates to the NIS+ database.  This is neccessary to ensure  the
       consistency of the backup.  For this reason, nisbackup should not be run while large numbers of updates are being applied to the NIS+ data-
       base. Update utilities such as  nisaddent(1M) should not be run simultaneously with nisbackup.

OPTIONS

       -a	Creates a backup of all NIS+ directory objects for which this server is a  master.

       -v	Verbose option. Additional output will be produced and sent to syslog(3C) upon execution of the command (see  syslog.conf(4)).

OPERANDS

       backup-dir      The directory into which the subdirectories containing the backed up objects  are placed. This must  be	created  prior	to
		       running	nisbackup.

       directory       The NIS+ directory object(s) being backed up.

EXAMPLES

       Example 1: Backup of the  org_dir NIS+ directory object of the domain  foo.com on a master server to a directory named  /backup

       To backup the  org_dir NIS+ directory object of the domain  foo.com on a master server to a directory named  /backup:

       master_server# nisbackup /backup org_dir.foo.com.

       Example 2: Backup of the entire NIS+ domain  foo.com to a directory named  /backup

       To backup the entire NIS+ domain  foo.com to a directory named  /backup:

       master_server# nisbackup /backup foo.com. 
		     org_dir.foo.com. groups_dir.foo.com. 
		     ctx_dir.foo.com.

       Example 3: Backup of an entire NIS+ database to a backup directory named /backup

       To backup an entire NIS+ database to a backup directory named /backup:

       master_server# nisbackup -a /backup

EXIT STATUS

       0	Successful completion.

       1	An error occurred.

FILES

       /backup-dir/backup_list

	   This ascii file contains a list of all the objects contained in this  backup-dir directory.

       /backup-dir/directory-object

	   A subdirectory that is created in the  backup-dir that contains the NIS+ directory-object backup.

       /backup-dir/directory-object/data

	   A subdirectory that contains the data files that are part of the  NIS+ directory-object backup.

       /backup-dir/directory-object/last.upd

	   This data file contains timestamp information about the directory-object.

       /backup-dir/directory-object/data.dict

	   A NIS+ data dictionary for all of the objects contained in the NIS+	 directory-object backup.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWnisu			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       nis+(1), nisdefaults(1), nisrm(1), nisrestore(1M), rpc.nisd(1M),  syslog(3C), nisfiles(4), syslog.conf(4), attributes(5)

NOTES

       NIS+  might  not  be  supported in future releases of the SolarisTM Operating Environment. Tools to aid the migration from NIS+ to LDAP are
       available in the Solaris 9 operating environment. For more information, visit http://www.sun.com/directory/nisplus/transition.html.

SunOS 5.10							    12 Dec 2001 						     nisbackup(1M)