Initial RAM disk image ( initrd )
Once the second stage boot loader has determined which kernel to boot, it locates the corresponding kernel binary in the /boot/ directory. The proper binary is the /boot/vmlinuz-2.6.x-xx file that corresponds to the boot loader’s settings.
Next the boot loader places the appropriate initial RAM disk image, called an initrd, into memory. The initrd is used by the kernel to load any drivers not compiled into it that are necessary to boot the system. This is particularly important if you have SCSI hard drives or are using the ext3 file system.
Tags: disk, image ( initrd ), Initial, RAM
Debugging on part(s) of the bash script
Using the set Bash built-in you can run in normal mode those portions of the script of
which you are sure they are without fault, and display debugging information only for troublesome zones.
Say we are not sure what the `uptime` command will do in a script, then we could enclose it in the script like this:
set -x # activate debugging from here
uptime
set +x # stop debugging from here
Tags: bash, debugging, part(s), Script
How to find IPs and IP networks behind each interface
To find the IPs of your network interfaces use ip addr show and to find the IP networks behind each interface use ip route show.
$
ip addr show
1: lo: mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
2: eth0: mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 1000
link/ether 00:08:74:22:5c:61 brd ff:ff:ff:ff:ff:ff
inet 192.168.1.2/24 brd 192.168.1.255 scope global eth0
inet 192.168.1.4/24 brd 192.168.1.255 scope global secondary eth0:1
#
ip route show
192.168.52.12 dev ppp0 proto kernel scope link src 117.114.119.119
192.168.1.0/24 dev eth0 proto kernel scope link src 192.168.1.1
169.254.0.0/16 dev eth0 scope link metric 1000
default dev ppp0 scope link
Tags: interface, IP, IPs, networks
How to check if Python script engine is enabled
We can check using the default Parallels Plesk Panel domain page content (http://domain.tld/index.html) - then by the “Python” item.
The test looks successful if a page with a list of environment variables is shown.
Test can be done using a simple script like this.
#!/usr/bin/env python
# -*- coding: UTF-8 -*-
# enable debugging
import cgitb
cgitb.enable()
print “Content-Type: text/plain;charset=utf-8″
print
print “Hello World!”
It is necessary to put the content into a text file and save in the domain web-accessible folder (like $HTTPD_VHOSTS_D/domain.tld/httpdocs) on the server with .py extension (test.py for example). Then try to open the file via browser by the http://domain.tld/test.py URL.
The test looks successful if a page shows the “Hello World!” string. If an error or full script listing is visible, it means that Python engine is not configured for the domain properly.
Reference: http://parallels.com/
Tags: check, engine, Python, Script
Unable to open configuration file /etc/psa/psa.conf: Permission denied
unable to open configuration file /etc/psa/psa.conf: Permission denied
Such errors are reported when Panel spam-filter processes incoming mail to mailbox with the Spamassasin feature enabled. Error is reported because spam-filter hook has no permission to access files in the /etc/psa directory. However, Spamassassin still processes messages correctly so this error does not mean Spamassassin is not working.
To workaround the issue it is possible to add the execute permissions for the /etc/psa folder.
Reference: http://parallels.com/
Tags: /etc/psa/psa.conf, configuration, denied, file, Open, Permission
