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"Automater"
Tech Tip: Running Scripts From cron
In some cases you may want to have a script scheduled to run from cron.
An example may be backing up IOS configurations on a nightly or
weekly basis or running the pinger script to verify any-to-any
connectivity. The pinger script can also be configured to only
confirm connectivity between several critical locations in the
network. Here, you may want to run this script more
frequently, perhaps every 15 or 30 minutes.
This tech tip will explain the configuration steps needed to run
a script from a Unix/Linux system using cron. (Note, the trial version will not work
with cron). The example used for demonstration purposes will
be backing up router configurations every Saturday at 2:00 AM. It is assumed the end user installation steps at
the beginning of the User's Manual were performed. This
example also assumes the user's script directory is
/export/home/jsmith/net-scripts.
First, you will need to have a login/password file configured to
store login and password information. (See the User's Manual for
more on the login/password file). If this is a production
environment, it is highly recommended that the login/password file
be encrypted using the encrypt_logins utility/script. When
encrypting a login/password file that will be used for cron, you
must use the -nokey option. You can run the encrypt_logins
utility from the GUI or the comamnd line.
Here is an example of running the encrypt_logins script from the
command line:
[net-scripts]$
encrypt_logins -if logins.var -of encr_logins.var -nokey
*******************************************************
* For more information about Script Automation
* or support issues, contact Technical Support
* E-mail: support@net-sense.com
*******************************************************
Please enter encryption key. You have 90 seconds
The un-encrypted password file is still on the system
This is a security risk!!
Do you wish to remove the un-encrypted password
file now? (yes/no)? yes
--------------------------
--------------------------
Script Complete
--------------------------
--------------------------
[net-scripts]$
Next, setup a soft-link for the setup.var file. (Note, the
setup.var file should all ready exist in $HOME/net-scripts). From
the Unix command line, perform the following. (Also note, this is a
one time configuration step)
[net-scripts]$
ln -s $HOME/net-scripts/setup.var
$HOME/setup.var
Perform the next step using your favorite text editor (vi, emacs,
GUI Text Editor, etc.)
In the directory $HOME/net-scripts create a new file called
config_backup.sh (any filename will do) and enter the
information below. This file is actually a small shell script. (Note, the script name
[copy_to_tftp] and the
arguments must all be on a single line when creating this file).
#!/bin/sh
D=`date +%m%d%y`
P="/export/home/jsmith/net-scripts"
/usr/local/net-sense/bin/copy_to_tftp -log ${P}/copy_to_tftp_${D}.log
-pw ${P}/encr_logins.var -rf ${P}/routers.rt -ipaddr 10.1.1.1 -subdir configs/${D}
-tftproot
/tftpboot -nokey
Here are some more details about the script arguments being used:
 | -log ${P}/config_bkup${D}.log This is the detailed
trace filename. Note, the -log argument is optional but in
this case the log file would get overwritten for each subsequent
run if we did not use this argument. The ${D) will get
replaced with the date. The ${P} will get replaced with the
Path specified by the variable P. |
| -pw ${P}/encr_logins.var This is the name of the
login/password file. Note, here it is encrypted. |
| -rf ${P}/routers.rt The file routers.rt
contains a list of routers or IP Addresses. One Router/IP
Addresses per line. If the router name its defined in DNS or
/etc/hosts file, then the name can be used in this file. |
| -ipaddr 10.1.1.1 This is the IP Address of
the TFTP server. In this case, the system running the script
must also be the TFTP server. This is always the case when
the script is using the arguments to create directories and
"touch" a blank file. (Put in your IP addresses) |
| -subdir configs/${D} This is the sub-directory, under
the default TFTP directory, that the configs will be saved to.
Each day the script is run, a new directory will be created so the
older config files are not over written. |
| -tftproot /tftpboot This is the default TFTP
directory configured on the system. Note, your system may
have a different default TFTP server directory name than /tftpboot. |
| -nokey This is needed because the
login/password file (logins.var) was encrypted which would
normally result in the user be prompted for an encryption key.
Using this option tells the script not to prompt for an encryption
key. Remember, you must create the encrypted login/password
file with the -nokey option, in order to use this option in a
script. |
Make the file, just created, an executable:
[net-scripts]$
chmod 755 config_backup.sh
Next, create a cron entry that calls the executable file
config_backup.sh. There are different ways to create cron
entries. Some of the more recent Unix/Linux OSs offer a GUI for
cron (e.g. Kcron). In the directory $HOME/net-scripts,
create a file called net-sense.cron and add the following entry:
30 2 * * 6
/export/home/jsmith/net-scripts/config_backup.sh
The above line tells cron to run the shell script
config_backup.sh every Saturday at 2:30 AM.
Note, in version 4.3.1 of The Automater, and later, you
will need to set the PATH variable in cron to also
look in the /usr/local/net-sense/bin directory (or wherever
The Automater executables were installed). The setting of the
PATH variable in cron varies between some UNIX and Linux systems.
For Linux, you can just add the following line (or something
similiar) to the top of the file net-sense.cron
PATH=/usr/bin:/bin:/usr/local/net-sense/bin
For a Solaris 2.8 system, you would need to to add
the following line to the file /etc/default/cron.
In addition for Solaris, you may have to kill the cron process and
restart it, in order for the new PATH variable to take effect.
Performing a kill -1 or kill a kill with the "nohangup" option may
not work.
PATH=/usr/sbin:/usr/bin:/usr/local/net-sense/bin
The basic idea is you just need to add the /usr/local/net-sense/bin
to the default PATH that cron all ready uses. To see the
default PATH that cron all ready uses, view the following files
(depending on OS):
Viewing Default PATH for CRON
| Operating System |
File |
| Solaris 2.8 |
/etc/default/cron |
| Suse Linux 10.1 |
/etc/crontab |
| RedHat 4.0 |
/etc/crontab |
Finally, tell cron to read this file
[jsmith]$ cd $HOME/net-scripts
[net-scripts]$
crontab net-sense.cron
You can issue the command crontab -l to see your current cron
jobs!
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