Here is an error message logged in /var/log/user.log and found on a linux box running Ubuntu 9.10

auditd: /sbin/audispd permissions should be 0750

Auditd is a daemon which belongs to the auditd package. This package contains a bunch of user utilities to store and analyze all what it is being logged by the audit subsystem in the Linux 2.6 kernel.

The only thing to do for this release version of Ubuntu :

root@localhost:~# ls -l /sbin/audispd
-rwxr-xr-x 1 root root 96020 2009-09-10 00:52 /sbin/audispd

root@veronique-desktop:~# ls -l /sbin/audispd
-rwxr-x— 1 root root 96020 2009-09-10 00:52 /sbin/audispd

root@veronique-desktop:~# dpkg-reconfigure auditd
update-rc.d: warning: auditd start runlevel arguments (S) do not match LSB Default-Start values (2 3 4 5)
update-rc.d: warning: auditd stop runlevel arguments (0 6) do not match LSB Default-Stop values (0 1 6)

While using mondorescue to perform a full backup of a server running RHEL 5, here is a list of error messages found in /var/log/mondoarchive.log :

File descriptor 3 (/tmp/mojo-jojo.blah.qN83BE) leaked on lvm invocation. Parent PID 3006: /bin/bash
File descriptor 3 (/tmp/mojo-jojo.blah.qN83BE) leaked on lvm invocation. Parent PID 3049: /bin/bash
File descriptor 3 (/tmp/mojo-jojo.blah.qN83BE) leaked on lvm invocation. Parent PID 3109: /bin/bash
File descriptor 3 (/tmp/mojo-jojo.blah.qN83BE) leaked on lvm invocation. Parent PID 3129: /bin/bash
File descriptor 3 (/tmp/mojo-jojo.blah.qN83BE) leaked on lvm invocation. Parent PID 3196: /bin/bash
File descriptor 3 (/tmp/mojo-jojo.blah.qN83BE) leaked on lvm invocation. Parent PID 3268: /bin/bash
File descriptor 3 (/tmp/mojo-jojo.blah.qN83BE) leaked on lvm invocation. Parent PID 3326: /bin/bash
File descriptor 3 (/tmp/mojo-jojo.blah.qN83BE) leaked on lvm invocation. Parent PID 3385: /bin/bash
File descriptor 3 (/tmp/mojo-jojo.blah.qN83BE) leaked on lvm invocation. Parent PID 3450: /bin/bash
File descriptor 3 (/tmp/mojo-jojo.blah.qN83BE) leaked on lvm invocation. Parent PID 3512: /bin/bash
File descriptor 3 (/tmp/mojo-jojo.blah.qN83BE) leaked on lvm invocation. Parent PID 3574: /bin/bash
File descriptor 3 (/tmp/mojo-jojo.blah.qN83BE) leaked on lvm invocation. Parent PID 3631: /bin/bash
File descriptor 3 (/tmp/mojo-jojo.blah.qN83BE) leaked on lvm invocation. Parent PID 3687: /bin/bash
File descriptor 3 (/tmp/mojo-jojo.blah.qN83BE) leaked on lvm invocation. Parent PID 3749: /bin/bash
File descriptor 3 (/tmp/mojo-jojo.blah.qN83BE) leaked on lvm invocation. Parent PID 3805: /bin/bash
File descriptor 3 (/tmp/mojo-jojo.blah.qN83BE) leaked on lvm invocation. Parent PID 3861: /bin/bash

After googling a little bit, here is the first explanation I managed to find. It seems that the lvm utility inherited all the opened file descriptors from the shell where it was launched.

By default, only three file descriptors are opened : 0 standard input,  1 standard output and 2 error output. So, a file descriptor named 3 was opened by a program but not closed properly.

A similar bug was reported within the official Debian bugreport :

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=466138

Such as lspci, lshw, discover is a hardware identification system based on the libdiscover2 library.
The available version for Debian lenny is the following one : 2.1.2-3

To install it :

root@localhost:~# apt-get install discover

It will install the following extra packages : discover-data libdiscover2

To use it, run the command /sbin/discover as root or with an user having sufficient privileges.
To get a summary of the devices found on the different buses :

root@localhost:~# discover -b

To make a search by device type :

root@localhost:~# discover -t network
Realtek Semiconductor Co., Ltd. RTL-8110SC/8169SC Gigabit Ethernet

More information : man discover
http://packages.debian.org/lenny/discover

If you want to perform  redirection of a command run by sudo, you will get the following error :

The file access permissions do not allow the specified action 0403-005 Cannot create the specified file

What does it mean?

Redirection is some kind of built-in features of your current running shell. (bash or ksh). When you issue a command with sudo, the built-in fonctions can not work within the child process.  To overcome this issue, the only workaround is to launch your command within a subshell :

sudo sh -c ‘your command > file.out’

If you change the appareance of your GNOME desktop, Debian provides two packages : gnome-themes and gnome-themes-extras
To install them :

root@localhost:~# apt-get install gnome-themes gnome-themes-extras

To choose one of the available themes :

fool@localhost:~$ /usr/bin/gnome-appearance-properties &

Here is what you should have :

To install other GNOME themes, please visit : http://gnome-look.org/
On this website, you can find plenty of wallpapers, icons, GTK2.x Themes/Styles. If you want to have a new full GNOME theme, just choose GTK2.x Themes/Styles : http://gnome-look.org/?xcontentmode=100

To install some of them, download your new theme archive and then install it by clicking on the button “Install…” as shown in the picture above. The installation is automatic and the new theme is available right away.

If you want to use FTP commands through a secured login session, here is a solution : sftp. SFTP can be activated on a remote server running openssh-server so that you will be able to run any  FTP commands.

All you have to do is to add the following line into the openssh server configuration file /etc/ssh/sshd_config :

root@localhost:~# echo “Subsystem       sftp    /usr/libexec/openssh/sftp-server” >> /etc/ssh/sshd_config

Reload you configuration file :

root@localhost:~# /etc/init.d/sshd reload

To open a ftp session :

sftp username@server_name

You will be in your default home directory. For instance, if you want to download a file on your own computer, use the get command.

To leave your session, just type quit.

All the modules available for the running kernel are located in the following directory : /lib/modules/$(uname -r)/

In this directory, there are several important files such as modules.pcimap and modules.usbmap. These files are created by depmod. They list all the modules available for the current kernel with the corresponding vendor id/model id of every hardware component which can be plugged to a PCI or USB bus.

Let’s have an example. I want to know which module to load for my fibre channel card (HBA) :

fool@localhost:~$ lspci |grep -i fibre

08:01.0 Fibre Channel: QLogic Corp. ISP2422-based 4Gb Fibre Channel to PCI-X HBA (rev 02)
08:01.1 Fibre Channel: QLogic Corp. ISP2422-based 4Gb Fibre Channel to PCI-X HBA (rev 02)

To get their respective vendor id/model id for each of them :

fool@localhost:~$ lspci -n |grep 08:01.0

08:01.0 0c04: 1077:2422 (rev 02)

Using the model id value, I can find the requested module’s name :

fool@localhost:~$ grep 2422 modules.pcimap
qla2xxx              0×00001077 0×00002422 0xffffffff 0xffffffff 0×00000000 0×00000000 0×0
The approach can be reused for usb devices using the modules.usbmap file.

If you get an error message as below :

sudo: /etc/sudoers is owned by gid 5876, should be 0

(The GID number is here just an example)
The group owner of the file /etc/sudoers is not the good one. As root, do the following change :

root@localhost:~#chown root:root /etc/sudoers

Check whether this file has the good rights otherwise :

root@localhost:~# chmod 0440 /etc/sudoers

Here is a message which was appearing in my syslog file until I solved the problem :

[drm] Initialized drm 1.1.0 20060810
mtrr: type mismatch for e0000000,10000000 old: write-back new: write-combining

MTRR stands for Memory Type range registers. Its a new feature available in the latest Intel processors.It is a new way of partitioning and managing memory resources in your system.There are two solutions for using the right values for mtrr.
The first one is to add this option to your grub command line :  enable_mtrr_cleanup mtrr_spare_reg_nr=1
The second one is to recompile your current kernel and choose the value 1 instead of 0 for MTRR cleanup enable value (0-1) while issuing the command make menuconfig.

I chose the first solution and I do not get any error messages no more :

dmesg |grep mtrr
[    0.000000] MTRR default type: uncachable
[    0.000000] MTRR fixed ranges enabled:
[    0.000000] MTRR variable ranges enabled:
[    0.000000] original variable MTRRs
[    0.000000] Found optimal setting for mtrr clean up
[    0.000000] New variable MTRRs
[    0.000000] Kernel command line: root=/dev/sda2 ro quiet enable_mtrr_cleanup mtrr_spare_reg_nr=1

For more information :
http://en.gentoo-wiki.com/wiki/MTRR
https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/314928
https://help.ubuntu.com/community/AspireOneDiscussion
http://www.phoronix.com/forums/showpost.php?p=74238&postcount=5
http://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/en-US/Reference_Guide/s2-proc-mtrr.html