When lilo fails to boot or there's a problem with MBR

Boot with Slackware install DVD, tested with 13.37 (only one I had to hand).


At boot prompt, follow instructions to boot existing system, something like;

huge.s root = /dev/sda1

Once system boots, we need to do the following:
Set keyboard map and login as root (no password).
cfdisk shows partitions (note root partition)

mount /dev/sda1 /mnt # where sda1 is the root partition. (discovered from cfdisk)

No need to mount any other partitions unless you need to make other changes.

The following was not needed but is documented as part of the process:

mount -o bind /dev /mnt/dev
mount -o bind /proc /mnt/proc
mount -o bind /sys /mnt/sys

chroot /mnt /bin/bash


Once in here you can edit /etc/lilo.conf
Note, in the case of SCS, location of boot bitmap needed to be changed to /boot/...

I choose to have at least 2 working kernels listed in there one at /dev/hda1 and one at /dev/sda2
this was due to the system showing current disk as sda and I knew original system showed as hda
I leave boot= flag untouched.

install lilo using lilo -b /dev/sda
and reboot, removing Slackware installation DVD


One of the kernel images should boot and then change lilo.conf back to normal and install lilo using lilo

UPDATE: 09 JULY 2021

On a 14.2 install with a failed lilo installation, I was able to follow the above but it would seem I was able to boot my system using;

huge.s root = /dev/sda1 rdinit=ro

and did not need to mount the root partition in order to make the changes, I was able to make a change to /etc/fstab.conf although in this case I didnt need to and was able to simply install lilo using lilo -b /dev/cciss/c0d0p

Additional notes, we can run fdisk -l and use that information to look in the /dev/* directory for where we should be installing lilo, in this case we have a raid setup so the usual /dev/sda wasn't going to cut it.

 

Linux mouse gpm

The following gets the mouse working in the console;

gpm -m /dev/input/mice -t imps2

https://www.linuxquestions.org/questions/slackware-14/setting-up-a-usb-mouse-in-slackware-401496/

put the following in rc.gpm and make bootable - chmod +x /etc/rc.d/rc.gpm

#!/bin/sh
# Start/stop the GPM mouse server:

if [ "$1" = "stop" ]; then
echo "Stopping gpm..."
gpm -k
else # assume $1 = start:
echo "Starting gpm..."
gpm -m /dev/mouse -t imps2
fi

Finally do ln -si /dev/input/mice /dev/mouse to create link
For usb /dev/mouse points to /dev/input/mice
For PS/2 /dev/mouse points to /dev/psaux


Optionally add/comment the following lines in /etc/X11/XF86Config for usb

#Option "Protocol"    "PS/2"
#Option "Device"      "/dev/psaux"
Option "Protocol" "imps/2"
Option "Device" "/dev/mouse"

Slightly related note: for keyboard, the following should be present:
#Option "XkbLayout"  "us"
Option "XkbLayout"  "uk"

Is network card is detected under linux

lspci -vv

or

lspci -vv | grep Ethernet

backup and restore mysql

Backup;

mysqldump -u [username] -p [databaseName] > [filename]-$(date +%F).sql

Restore; 

mysql -u [username] -p [databaseName] < [filename].sql

See here for more details...

Categorical and Continuous Variables - Nominal, Dichotomous, Ordinal, Interval, Ratio

Categorical and Continuous Variables

Categorical variables are also known as discrete or qualitative variables. Categorical variables can be further categorized as either nominal, ordinal or dichotomous.

Linux - remount filesystem rw

mount -o remount,rw / (might have used only w)

lilo.conf - Check boot parameter is correct /dev/sd* matches where drive is connected.
run lilo from /boot (if need be use lilo -b /dev/sd* where sda is the drive not the partition.
Check root = /dev/sd* is the correct partition

Check /etc/fstab has correct /dev/sd* entries
 

Protecting a directory with htaccess

Normalization Normal forms

First Normal Form 1NF

No repeating columns or columns contain only a single value.


Second Normal Form 2NF

As per 1NF but each non PK value can be uniquely identified by the PK

Third Normal Form 3NF

As per 2NF but each no PK value can ONLY be identified by the PK

Comparison between SQL and Pandas

Comparison with SQL

VirtualBox command line. Removing innaccessable VMs change machine location

To delete virtual machines from the command line, first I removed the *.vbox *.vmdk files etc (basically the folder that these files are in).

Then;
VBoxManage list vms (this lists virtual machines)
VBoxManage unregistervm ********* (where *** is the number of the VM as shown by the previous command).

To change default location of VM's
vboxmanage setproperty machinefolder /path/to/directory/
Note use path in quotation marks if folder needs a space, example;
vboxmanage setproperty machinefolder "/var/VirtualBox VMs"