Auxiliary Linux**-service-applications

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Last revision of this document:
2005-05-19

To reduce the number of documents, this document contains installation-instructions for usefull service-applications which need only short instructions.

Overview:

Shutdown of a computer after a predefined time

Mount directories on a remote computer (configuration in /etc/fstab)

Mount directories on a remote computer (using automount)

Copy data to be backed-up to the tape-cartridge

List data stored on a backup-tape

Restore data from a backup-tape to disk

Shutdown of a computer after a predefined time

A computer, which should not be running 24 hours / day can be switched off after a predefined running time.

Prerequisites:

Operating-system installed ;-).

`Installation-instruction:`

The file /etc/rc.d/rc.local is appended with the following command-lines:

# Automated shutdown of the computer after a predefined time # (in minutes) to perform a controlled unmount of the disks. shutdown -h 960 &

This calls the shutdown-command as a background-task during the start-up of the operating-system.

In the example above, 960 is the time in minutes until the shutdown takes effekt (16 hours in this example) and & is the parameter to perform the command as a background-task.

Additional hints:

The file can only be changed with access-rights as 'root'. That the change takes effect it is requiered to execute the file /etc/rc.d/rc.local or to restart Linux**. If the background-task should be stopped, the the user 'root' can use the command shutdown -c

Test:

After a new startup of Linux** it can be checked if shutdown already runs as a background-task with the following method: If you try to restart the computer with keyboard-key-combination Alt-Ctrl-Del, the message shutdown already running is displayed.

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Mount directories on a remote computer (configuration in /etc/fstab)

Directories on another computer (e.g. Server), which where allowed for to be acesses with the Network-File-System (NFS), can be mounted as local directories.

Mounting directories on a remote computer with this method makes sense only, if the NFS on the remote computer is already up and running when the operating-system is started on the workstation. This is due to the fact that /etc/fstab is read once only during the strartup of the operating system (Linux**).
If there might be cases that the NFS on the Server is not up during starting the operating-system on the workstation or the workstation ist not connected to the network during startup (e.g. the workstation is a notebook), then using Mount directories on a remote computer (using automount) is the better method.

Prerequisites:

Operating-system installed ;-).
A NFS-Server is running on the remote computer and directories are allowed to be accessed.
This can be checked by executing the command showmount -e 192.168.0.1 (as user 'root' on a command-line).
192.168.0.1 is the TCP/IP-address of the remote computer.

Linux-workstation - file-struture and users are defined on the computer where the remote directories should be mounted as local directories.

Installation-instruction:

Directories of the remote computer to be mounted as local directories are defined by appending the following lines in the file /etc/fstab:

192.168.0.1:/SMB_Disk/backup_mirror /_rmt-server/backup_mirror nfs rw,hard,intr 0 0 192.168.0.1:/SMB_Disk/data_backed_up /_rmt-server/data_backed_up nfs rw,hard,intr 0 0 192.168.0.1:/SMB_Disk/data_not_backed_up /_rmt-server/data_not_backed_up nfs rw,hard,intr 0 0 192.168.0.1:/SMB_Disk/finance /remote/_rmt-server/finance nfs rw,hard,intr 0 0 192.168.0.1:/SMB_Disk/progs_honest /_rmt-server/progs_honest nfs rw,hard,intr 0 0 192.168.0.1:/SMB_Disk/progs_writing /_rmt-server/progs_writing nfs rw,hard,intr 0 0

This allows to access a directory on the remote computer (e.g. 192.168.0.1:/SMB_Disk/backup_mirror) like are local directory (with the name /_rmt-server/backup_mirror in the above configuration).

Additional hints:

The file can only be changed with access-rights as 'root'. That the change takes effect it is requiered to restart Linux**. For security-reasons the access-rights do not allow the user 'root' to access the mounted directories. To access the mounted directories it is necessary to log on with a user-name which has access to the mounted directories.

Test:

Logged on as a user with access-right to the directories the command dir /remote/server/data_backed_up is issued and the content of the directory should be displayed.
Using a editor a file called mounttest is created on the directory /remote/server/data_not_backed_up. After successfully creating the file it can be deleted with the command rm /remote/server/data_backed_up/mounttest.

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Mount directories on a remote computer (using automount)

Directories on another computer (e.g. Server), which where allowed for to be acesses with the Network-File-System (NFS), can be mounted as local directories.

Mounting directories with this method is a safe one but less performant.
If it can be taken for sure that the NFS is running on the Server when the operating-system on the workstation is started-up, then the method Mount directories on a remote computer (configuration in /etc/fstab) is faster and more efficient.

Prerequisites:

Operating-system installed ;-).
A NFS-Server is running on the remote computer and directories are allowed to be accessed.
This can be checked by executing the command showmount -e 192.168.0.1 (as user 'root' on a command-line).
192.168.0.1 is the TCP/IP-address of the remote computer.

Linux-workstation – file-struture and users are defined on the computer where the remote directories should be mounted as local directories.

Installation-instruction:

Automatic starting of the automount-demon

To configure automatic startup the command
ntsysv
is executed on the command-line.

On the following 'Services'-menu the selection [ ] autofs is marked with the space-bar and the and confirmed with the OK-button.

Configuration of the 'Master'-file

The file /etc/auto.master will be append with the following lines:

/_rmt-server /etc/auto.server --timeout=60

This defines the local directory (/remote/server) and the file with the 'Indirect Maps' (/etc/auto.server) where the references to the directories on the remote computer (Server) will be defined. Please take care not to change or delete existing configuration-lines !!

Configuration of the 'Indirect-Map'-file (/etc/auto.server in this example)

The file /etc/auto.server will contain the following configuration-lines:

backup_mirror -browse,rw,soft,intr 192.168.0.1:/SMB_Disk/backup_mirror data_backed_up -browse,rw,soft,intr 192.168.0.1:/SMB_Disk/data_backed_up data_not_backed_up -browse,rw,soft,intr 192.168.0.1:/SMB_Disk/data_not_backed_up finance -browse,rw,soft,intr 192.168.0.1:/SMB_Disk/finance progs_honest -browse,rw,soft,intr 192.168.0.1:/SMB_Disk/progs_honest progs_writing -browse,rw,soft,intr 192.168.0.1:/SMB_Disk/progs_writing

This file in conjunction with /etc/auto.master mounts the remote directories (e.g. 192.168.0.1:/SMB_Disk/data_backed_up) to the subdirectory (e.g. data_backed_up) under the directory /remote/server (defined in /etc/auto.master). Please take care not to change or delete existing configuration-lines !!

Additional hints:

The file can only be changed with access-rights as 'root'. That the change takes effect it is requiered to restart the service with the command /etc/init.d/autofs reload or to restart Linux**. For security-reasons, the access-rights do not allow the user 'root' to access the mounted directories. To access the mounted directories it is necessary to log on with a user-name which has access to the mounted directories.

Test:

Logged on as a user with access-right to the directories the command dir /remote/server/data_backed_up is issued and the content of the directory should be displayed.
Using a editor a file called mounttest is created on the directory /remote/server/data_not_backed_up. After successfully creating the file it can be deleted with the command rm /remote/server/data_backed_up/mounttest.

Credits

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Copy data to be backed-up to the tape-cartridge

This part introduces a script, which copies all data from the directories /SMB_Disk/data_backed_up, /SMB_Disk/finance and /SMB_Disk/progs_writing to the directory /SMB_Disk/backup_mirror first and to a backup-tape thereafter.

Prerequisites:

Operating-system installed ;-).
The file- and user-structure as described in the document 'Linux-Server - file-structure and users' is already implemented on the Server.

Installation-instruction:

Create a file named /SMB_Disk/data_backed_up/system_scripts/linux/backup.sh and edit it with the following commands. (For an instruction how to copy the following text to a file please follow this link.)

#!/bin/sh ################### ### PURPOSE: Copies all directories with files to be backed-up ### to the dedicated directory and to a tape thereafter ################### # echo -n "Starting backup to tape ...." # # copy data to be copied to the directory /SMB_Disk/backup-mirror echo -n "Copy data to directory backup_mirror ..." # # Delete existing data by deleting whole directory backup_mirror # and re-create directory backup_mirror rm -fr /SMB_Disk/backup_mirror mkdir /SMB_Disk/backup_mirror # # Copy data to be backed_up cp -R /SMB_Disk/data_backed_up /SMB_Disk/backup_mirror cp -R /SMB_Disk/finance /SMB_Disk/backup_mirror cp -R /SMB_Disk/progs_writing /SMB_Disk/backup_mirror # # Change access-rights so, that only users belonging to group 'admin' are allowed to read (only) chgrp -R admin /SMB_Disk/backup_mirror chmod -R 440 /SMB_Disk/backup_mirror # # Copy data to backup-tape echo -n "Copy data to backup-tape ..." mt -f /dev/st0 rewind tar -cvMpf /dev/st0 /SMB_Disk/backup_mirror mt -f /dev/st0 offline echo "Data backed-up to tape; please remove the tape ..." # # # Uncomment the 'shutdown' command # if the backup is run at the end of day # and the computer should be switched off # shutdown -h now ### End of scripts ###

To protect the just created file against erratical change, give only read- and execution-rights to the owner (i.e. Root) by entering the following command at the terminal: chmod 500 SMB_Disk/data_backed_up/system_scripts/linux/backup.sh

Defining the start-time:

Starting at the begin of day

The previous script will be executed by appending the following lines to the file /etc/rc.d/rc.local :

# Copy selected data to the directory /SMB_Disk/backup_mirror # and furtheron to the backup-tape (dev/st0) /SMB_Disk/data_backed_up/system_scripts/linux/backup.sh &

This causes, that the script to backup data to the backup-tape will be called as background-task when the operating system is started.

Starting at a defined time

The previous script will be executed by using crontab. The following statement is added to the file /etc/crontab :

SHELL=/bin/bash . . . . . . 42 4 1 * * root run-parts /etc/cron.monthly # Backup data to tape (at 23:30 in this example) # using the script in file 'backup.sh'. 0 23 * * * root /SMB_Disk/data_backed_up/system_scripts/linux/backup.sh . . . . . .

This causes, that the script to backup data to the backup-tape will be called at the predefined time. Additionally, a 'shutdown' can be performed as soon as the backup is complete.

Additional hints:

The file can only be changed with access-rights as 'root'. That the change takes effect it is requiered to execute the file /etc/rc.d/rc.local (if the backup is performed at start-up) or to restart Linux**.

Test:

After a restart of the computer, data to be backed-up ist copied to the directory SMB_Disk/backup_mirror first and written to the backup-tape thereafter. If the data was written to the tape correctly can be checked as described under List data stored on a backup-tape.

Additional references:

List data stored on a backup-tape	This script shows the contents of a tape.
Restore data from a backup-tape to disk	This script restores all or selected files from a backup-tape back to the harddisk.

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List data stored on a backup-tape

This part introduces the command to list the files backed-up on a tape.

Prerequisites:

Operating-system installed ;-).
Files must be backed-up with the command 'tar'.
How to inspect, which kind of archives a tape contains is described under 'http://nic.phys.ethz.ch/readme/80#6'.

Command-instruction:

Open a Terminal-window and enter the following command:

tar tvf /dev/st0

If you want to list just the files of a directory, give the the complete path of the directory. The following command is an example:

tar tvf /dev/st0 SMB_Disk/backup_mirror/data_backed_up/Download/jdk_jre/*

Additional hints:

The command can only be executed with access-rights as 'root'. If the tape contains numerous files, it is advisable to open a Terminal-window under the GUI. The Terminal-window is not restricted on lines to display and therefore the display of a file-name is not scrolled out of the screen after a while. Rewind the tape (command mt -f /dev/st0 rewind) before listing the files. You need some patience to see a result as the tape has to be winded forward completely to check the contents of the tape.

Test:

Watch if the selected files are listed on the Terminal-Window.

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Restore data from a backup-tape to disk

This part introduces the command to list the files backed-up on a tape.

Prerequisites:

Operating-system installed ;-).
Files must be backed-up with the command 'tar'.
How to inspect, which kind of archives a tape contains is described under 'http://nic.phys.ethz.ch/readme/80#6'.

Command-instruction:

Open a Terminal-window and enter the following commands:

Rewind the tape:

mt -f /dev/st0 rewind

Go to the top-directory if you want to restore to the original directory/ies; if you want to restore to another directory - change to this directory:

cd /

Issue the command to restore the complete set of files from the tape:

tar xvf /dev/st0

If you want to restore just the files of a directory, give the the complete path of the directory. The following command is an example:

tar xvf /dev/st0 SMB_Disk/backup_mirror/data_backed_up/Download/jdk_jre/*

If you want to restore just a single file, give the filename including the complete path. The following command is an example:

tar xvf /dev/st0 SMB_Disk/backup_mirror/data_backed_up/office/invoices/570021.sxw

Additional hints:

The command can only be executed with access-rights as 'root'. If the tape contains numerous files, it is advisable to open a Terminal-window under the GUI. The Terminal-window is not restricted on lines to display and therefore the display of a file-name is not scrolled out of the screen after a while. If you restore just singele directories or files, you need some patience to see a result as the tape has to be winded forward until the selected files or directories have been found.

Test:

Check if the selected files are in the correct directory on the harddisk.

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