Tag: linux

To redirect old site to new url using .htacces, use following

RewriteCond %{HTTP_HOST} ^old-url.com$ [OR]
RewriteCond %{HTTP_HOST} ^www.old-url.com$
RewriteRule (.*)$ http://www.new-url.com/$1 [R=301,L]

See htaccess

To list kernal modules, use

lsmod

Example

boby@sok-01:~$ lsmod | grep rtl
rtl8xxxu              122880  0
mac80211              778240  2 ath9k_htc,rtl8xxxu
boby@sok-01:~$ 

To log commands executed by users on Linux shell, edit file

vi /etc/bash.bashrc

Add

export PROMPT_COMMAND='RETRN_VAL=$?;logger -p local6.debug "$(whoami) [$$]: $(history 1 | sed "s/^[ ]*[0-9]\+[ ]*//" ) [$RETRN_VAL]"'

Create file

vi  /etc/rsyslog.d/bash.conf

Add

local6.*    /var/log/commands.log

Restart rsyslog

systemctl restart rsyslog

Now log off and login, you will be able to see all commends executed by users on bash shell in file /var/log/commands.log

Log rotating

edit

vi /etc/logrotate.d/rsyslog

Find

/var/log/kern.log

Add below

/var/log/commands.log

xinput command on linux shows all available input devices.

xinput

Example

CentOS
Ubuntu
Debian
ArchLinux
openSUSE

Try Linux distro with out downloading ISO

Partitioning hard disk for backup

It is better to have a second hard disk on servers for backup. Here, we will partition a fresh disk, format and mount it as /backup.

parted /dev/sdX print free
parted /dev/sdX mktable gpt
parted /dev/sdX mkpart primary ext4 0% 100%
mkfs.ext4 /dev/sdX1

Replace /dev/sdX with the actual device name of your backup disk.

Now you need to find the UUID for this new drive with the command

blkid

Create a folder to mount the disk, in this case, we use /backup

mkdir /backup

Edit /etc/fstab

vi /etc/fstab

Add

UUID=1c7b33ed-ea6d-4694-9925-edfd0e8a2837  /backup ext4 defaults 0 1

Replace “1c7b33ed-ea6d-4694-9925-edfd0e8a2837” with the actual UUID for your new disk, that you found using blkid command.

Now run

mount -a

This will mount all disks specified in /etc/fstab, verify /backup is mounted with the command

df -h

Partitioning New HDD

Here we partition the device /dev/sdb and mount it as /backup.

First, we check free space on the server with

[root@sok ~]# parted /dev/sdb print free
Error: /dev/sdb: unrecognised disk label
Model: ATA WDC WD1003FBYX-0 (scsi)                                        
Disk /dev/sdb: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: unknown
Disk Flags: 
[root@sok ~]#

Lets make the partition table of type GPT

[root@sok ~]# parted /dev/sdb mktable gpt
Information: You may need to update /etc/fstab.

[root@sok ~]#

Now you will see we have 1000 GB free space.

[root@sok ~]# parted /dev/sdb print free                                
Model: ATA WDC WD1003FBYX-0 (scsi)
Disk /dev/sdb: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 

Number  Start   End     Size    File system  Name  Flags
        17.4kB  1000GB  1000GB  Free Space

[root@sok ~]#

Let’s create a partition of type ext4 using 100% of the disk.

[root@sok ~]# parted /dev/sdb mkpart primary ext4 0% 100%
Information: You may need to update /etc/fstab.

[root@sok ~]# parted /dev/sdb print free                
Model: ATA WDC WD1003FBYX-0 (scsi)
Disk /dev/sdb: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 

Number  Start   End     Size    File system  Name     Flags
        17.4kB  1049kB  1031kB  Free Space
 1      1049kB  1000GB  1000GB               primary
        1000GB  1000GB  729kB   Free Space

[root@sok ~]#

Formatting the Disk

[root@sok ~]# mkfs.ext4 /dev/sdb1
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
61054976 inodes, 244190208 blocks
12209510 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2392850432
7453 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks: 
	32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 
	4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968, 
	102400000, 214990848

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done     

[root@sok ~]# 

Mounting Disk

First, find the UUID of the disk with command blkid

[root@thor ~]# blkid
/dev/sda2: UUID="aba6f962-366b-455a-959a-b9d04a9bfa34" TYPE="ext4" 
/dev/sda1: UUID="3432e015-01e6-4f09-9991-ff73a90f340b" TYPE="swap" 
/dev/sdb1: UUID="1c7b33ed-ea6d-4694-9925-edfd0e8a2837" TYPE="ext4" PARTLABEL="primary" PARTUUID="7c182896-e88f-44cf-b3fe-e369b88044a1" 
/dev/loop0: UUID="63f812e0-51e0-4cf8-8ae4-da70d61ce272" TYPE="ext3" 
/dev/sdd1: UUID="5cabe12d-a575-4374-af15-c8bb3abe8fe8" TYPE="ext4" PARTLABEL="primary" PARTUUID="0eca4648-25a4-4b89-a93b-bc3ad781caa0" 
/dev/sdc1: UUID="01cc1cfd-888b-42e2-bb1c-e0461c6b989d" TYPE="ext4" PARTLABEL="primary" PARTUUID="74cd1045-fbfc-44a0-9a7d-e0965db53d06" 
[root@thor ~]# 

UUID for the disk /dev/sdb1 is

UUID="1c7b33ed-ea6d-4694-9925-edfd0e8a2837"

To mount this disk as /backup, first create a folder

mkdir /backup

Now edit /etc/fstab

vi /etc/fstab

Add the following line

UUID=1c7b33ed-ea6d-4694-9925-edfd0e8a2837  /backup ext4 defaults 0 1

Run

mount -a

This will mount all disks specified in /etc/fstab

Verify your new drive is mounted with the command df -h

[root@thor ~]# df -h | grep backup
/dev/sdb1       917G   77M  871G   1% /backup
[root@thor ~]# 

Linux How to Disable a user account
useradd
usermod
Adding a group in Linux with addgroup
Linux groups

To disable or lock a linux user account, run

passwd -l USERNAME_HERE

Or

usermod -L USERNAME_HERE

To verify if a user is locked, run

passwrd --status USERNAME_HERE

If account is disabled/locked, it will show L.

By default files are displayed with “Icon View”

I prefer list view.

To set default view in Nemo, go to

Edit -> Preferences -> Views (tab) -> View new folders using -> List View