We use syslog-ng with remote logging to keep track of our logs. The targeted policy doesn't allow syslog-ng to operate by default. The following lines added to local.te in /etc/selinux/targeted/src/policy/domains/misc will allow syslog-ng to bind to port 514 and access proc kmsg for kernel messages (such as avc messages!)

We have a few RHEL4 servers, logs fail to rotate on the production machines, but not unmodified machines. We discovered that this is a known bug with using noexec on /tmp https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=156594 If you change your /tmp mount to noexec, logrotate cannot work because it tries to execute a script in /tmp to do the rotation. The hack to get it working is to add a TMPDIR in the cron job that runs logrotate (and create a directory that it can execute a script in, mkdir /root/tmp; chm

I prefer a high speed serial connection to the normal 9600, we use 115200 of 57600.

Console Redirection in Bios

To see the post messages and access your bios setup screens, enable console redirection in the bios if available

Grub

Modify /boot/grub/grub.conf to enable serial console Add: serial --unit=0 --speed=115200 terminal Add to kernel line: console=tty0 console=ttyS0,115200n8 Remove: splashimage hiddenmenu

Booted System

Start a getty process on ttyS0 at the same speed specified in grub.conf

We have a few machines with console redirection in the bios. We access these with minicom. To enter the bios, we've found that the VT100 escape sequences work. To send F1, enter ESC O P, the capitalization on the O and P are essential. Other codes that are known to work:

F1	^[OP
F2	^[OQ
F3	^[OR
F4	^[OS

F12 comes through unharmed, so to get the boot menu on most machines, we just type F12 directly.

We have a few departments on campus and each user has a username in at least one department plus the top level domain. This means that if an email is sent to username@dept.company.net and there is a cc to username@company.net Then username will get the email twice. After playing around I found that procmail can track the messageid's of emails in a file, so i have this simple rule to filter out. PMDIR=$HOME/.procmail :0 Whc: msgid.lock | formail -D 4096 $PMDIR/idcache :0 a: Mail/duplicates

:0 Whc: msgid.lock This sends the headers t

After installing the cluster stuff (GFS), lvscan and lvdisplay stopped working with the following error: [uphill@zürich]: lvscan connect() failed on local socket: Connection refused Locking type 2 initialisation failed.

It sometimes comes up that the usual trick of reading in a stream with a pipe and a while loop doesn't work, since the pipe causes a subshell and any variables set in the subshell are unavailable to the parent.
For example the normal trick (output the first few lines of the /etc/services file, just the first two columns and not empty or comment lines):

[uphill@zagreb]: grep -v ^# /etc/services | grep -v ^$ | head | awk '{print $1" "$2;}'
tcpmux 1/tcp
tcpmux 1/udp
rje 5/tcp
rje 5/udp
echo 7/tcp
echo 7/udp
discard 9/tcp
discard 9/udp
systat 11/tcp
systat 11/udp


Sometimes it's easier to write a quick script in bash that uses arrays rather than figure out how to do it with something more appropriate like awk or perl.

It's really very quick and simple. To start, declare your variable as an array


[uphill@host]: declare -a myvar


If the array is going to be global then add x to export it.

In RHEL4 and possibly other distros. The .Xdefaults file is not used, the file is now called .Xresources In /etc/X11/xinit/xinitrc-common, xrdb is passed .Xresources _after_ /etc/X11/Xresources. You can make systemwide changes in /etc/X11/Xresources, but they will be overridden by changes to .Xresources.

I'm hoping that someone else has a better solution for this one. We have a pocketpoint remote that works quite well for Power point presentations, but for Acrobat Reader the keybinding is not good. The remote sends p for prior/previous and n for next, which is understood by powerpoint and not by Adobe. I wrote the following lame script to fix this. It works for the most part, but you lose the p and n keys during the presentation. [includecode#../scripts/pocketpoint]