Category: Linux

nmcli
- How to add secondary IP address using nmcli
February 7, 2022

Resize EC2 file system with lvm

On an EC2 server with an LVM file system, I need to increase the size of the / partition. First, increase the size of the volume in the Amazon AWS console as per Resize Amazon EC2 Boot Disk, once volume size is increased, you need to resize your filesystem.

[root@sok ~]# df -h
Filesystem           Size  Used Avail Use% Mounted on
devtmpfs             3.8G     0  3.8G   0% /dev
tmpfs                3.8G     0  3.8G   0% /dev/shm
tmpfs                3.8G   17M  3.8G   1% /run
tmpfs                3.8G     0  3.8G   0% /sys/fs/cgroup
/dev/mapper/cl-root   38G   33G  5.1G  87% /
/dev/nvme0n1p1      1014M  412M  603M  41% /boot
tmpfs                775M     0  775M   0% /run/user/0
[root@sok ~]#

Here is result of parted -l

[root@sok ~]# parted -l
Model: Linux device-mapper (linear) (dm)
Disk /dev/mapper/cl-swap: 1074MB
Sector size (logical/physical): 512B/512B
Partition Table: loop
Disk Flags: 

Number  Start  End     Size    File system     Flags
 1      0.00B  1074MB  1074MB  linux-swap(v1)


Model: Linux device-mapper (linear) (dm)
Disk /dev/mapper/cl-root: 40.7GB
Sector size (logical/physical): 512B/512B
Partition Table: loop
Disk Flags: 

Number  Start  End     Size    File system  Flags
 1      0.00B  40.7GB  40.7GB  xfs


Model: NVMe Device (nvme)
Disk /dev/nvme0n1: 172GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start   End     Size    Type     File system  Flags
 1      1049kB  1075MB  1074MB  primary  xfs          boot
 2      1075MB  10.7GB  9663MB  primary               lvm
 3      10.7GB  16.1GB  5369MB  primary               lvm
 4      16.1GB  42.9GB  26.8GB  primary               lvm


[root@sok ~]#

/dev/nvme0n1 was resized to 172 GB, but the 4th partition was only using 26 GB.

Resize the 4th partition with the command “growpart /dev/nvme0n1 4”

[root@sok ~]# growpart /dev/nvme0n1 4
CHANGED: partition=4 start=31457280 old: size=52428800 end=83886080 new: size=304087007 end=335544287
[root@sok ~]# parted /dev/nvme0n1 print
Model: NVMe Device (nvme)
Disk /dev/nvme0n1: 172GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start   End     Size    Type     File system  Flags
 1      1049kB  1075MB  1074MB  primary  xfs          boot
 2      1075MB  10.7GB  9663MB  primary               lvm
 3      10.7GB  16.1GB  5369MB  primary               lvm
 4      16.1GB  172GB   156GB   primary               lvm

[root@sok ~]#

Resize physical volume with “pvresize /dev/nvme0n1p4” command.

[root@sok ~]# pvresize /dev/nvme0n1p4
  Physical volume "/dev/nvme0n1p4" changed
  1 physical volume(s) resized or updated / 0 physical volume(s) not resized
[root@sok ~]#

Finally resize logical volume with the command “lvextend -r -l +100%FREE /dev/mapper/cl-root”. -r option resize the file system also.

[root@sok ~]# lvextend -r -l +100%FREE /dev/mapper/cl-root
  Size of logical volume cl/root changed from 37.90 GiB (9703 extents) to <157.99 GiB (40445 extents).
  Logical volume cl/root successfully resized.
meta-data=/dev/mapper/cl-root    isize=512    agcount=19, agsize=524032 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0 spinodes=0
data     =                       bsize=4096   blocks=9935872, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal               bsize=4096   blocks=2560, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 9935872 to 41415680
[root@sok ~]#

Now the size of the / portion is increased to use full available disk space.

[root@sok ~]# df -h
Filesystem           Size  Used Avail Use% Mounted on
devtmpfs             3.8G     0  3.8G   0% /dev
tmpfs                3.8G     0  3.8G   0% /dev/shm
tmpfs                3.8G   17M  3.8G   1% /run
tmpfs                3.8G     0  3.8G   0% /sys/fs/cgroup
/dev/mapper/cl-root  158G   33G  126G  21% /
/dev/nvme0n1p1      1014M  412M  603M  41% /boot
tmpfs                775M     0  775M   0% /run/user/0
[root@sok ~]#

February 4, 2022

Run rsync if not running using cronjob
I want to rsync files from one server to another server every 5 minutes, but only want to start the rsync if the previous rsync command has finished. Time for one rsync depends on how much data changed on the source server, so the time taken to finish rsync cronjob varies.

Create file rsync.sh
```
#!/bin/bash

if ! pgrep -x "rsync" > /dev/null
then
    rsync -avzP /var/www/html/files/  [email protected]:/var/www/html/files/
fi
```
Set cronjob like
```
*/10 * * * * /root/rsync.sh > /dev/null
```
January 23, 2022
How to Install memcached on CentOS Plesk Server
Install memcached daemon with command
```
yum install Memcached
```
Enable memcached to start on boot
```
systemctl enable memcached
```
Start memcached
```
systemctl start memcached
```
You can verify if memcached is running with the command “netstat -lntp”
```
[root@server ~]# netstat -lntp |grep memcache
tcp        0      0 0.0.0.0:11211           0.0.0.0:*               LISTEN      129472/memcached    
tcp6       0      0 :::11211                :::*                    LISTEN      129472/memcached    
[root@server ~]#
```
By default Memcached listen on all interfaces (0.0.0.0:11211). You need to make it bind to 127.0.0.1 only, so no one will be able to access your Memcached installation from the public. For securing Memcached installation, refer How to secure Memcached on CentOS 7. After Memcached is secured, you will see it listen on 127.0.0.1 only like the following
```
[root@server etc]# netstat -lntp | grep mem
tcp        0      0 127.0.0.1:11211         0.0.0.0:*               LISTEN      81636/memcached     
[root@server etc]# 
```
Install memcached PHP Module

Install the requirements
```
yum install -y libmemcached-devel zlib-devel
```
Replace default system PHP with PHP version on which you need memcache PHP module installed. In this case, I will be installing the PHP module for PHP version 7.4
```
cd /usr/bin
mv php php.old
mv phpize phpize.old
ln -s /opt/plesk/php/7.4/bin/php
ln -s /opt/plesk/php/7.4/bin/phpize
```
Now run the command
```
/opt/plesk/php/7.4/bin/pecl install memcached
```
If you get error related to phpize missing, you need to install PHP devel package.
```
yum install plesk-php74-devel
```
After install finished, you need to edit php.ini
```
vi /opt/plesk/php/7.4/etc/php.ini
```
At end of the file, add
```
extension=memcached.so
```
Restart php-fpm
```
systemctl restart plesk-php74-fpm.service
```
Install memcache module

the latest version of memcache won’t work with PHP 7.4, so we need to use an older version.

To install version 4.0.5.2 of memcache, run
```
/opt/plesk/php/7.4/bin/pecl install memcache-4.0.5.2
```
After installing, edit php.ini file
```
vi /opt/plesk/php/7.4/etc/php.ini
```
At end of the file, add
```
extension=memcache.so
```
Restart php-fpm
```
systemctl restart plesk-php74-fpm.service
```
January 21, 2022
smartmontools
smartmontools is used to check the health of hard disks.

To install smartmontools on CentOS, run
```
yum install smartmontools
```
The command line for smartmontools is smartctl
January 20, 2022
How to verify installed packages on Ubuntu/Debian
To verify the integrity of installed packages, you can use debsums utility. First of all install debsums with command
```
apt install -y debsums
```
To verify packages, run
```
debsums -s
```
To verify a package
```
debsums PKG_NAME
```
If you find any packages with missing files, you can reinstall them with the command
```
apt reinstall PKG_NAME
```
January 19, 2022

sleep-monitor system is about to suspend

On a remote Linux server running XFCE desktop, the server goes down randomly, on monitoring /var/log/syslog, i found the following message

Jan 18 05:43:24 sokdesk ModemManager[1300]:   [sleep-monitor] system is about to suspend
Jan 18 05:43:24 sokdesk systemd[1]: Reached target Sleep.
Jan 18 05:43:24 sokdesk systemd[1]: Starting Record successful boot for GRUB...
Jan 18 05:43:24 sokdesk systemd[1]: Starting Suspend...
Jan 18 05:43:24 sokdesk systemd-sleep[2574]: Suspending system...
Jan 18 05:43:24 sokdesk kernel: [ 1217.283955] PM: suspend entry (s2idle)

When this happens, the remote desktop and SSH connections to the server get disconnected. To get back to the server, I had to restart the server.

The error is fixed by running the command

systemctl mask sleep.target suspend.target hibernate.target hybrid-sleep.target

January 18, 2022

View Past Performance Data With sar
sysstat stores past data in the directory
```
/var/log/sa - for RHEL based OS
/var/log/sysstat - for Debian based OS
```
Each day log files are stored in a file with the respective date.
```
sa01 - log file for day 1
sa31 - log file for day 31
```
To view logs for day 9, run
```
sar -f /var/log/sa/sa09
```
If you want to see entries during a specific time, you can use
```
sar -f /var/log/sa/sa09 -s hh:mm:ss
```
Example

You can specify end time with -e option

If you want to see IO data, use -b option
```
sar -f /var/log/sa/sa09 -b
```
January 11, 2022
Install PHP 7.2 mcrypt extension on CWP Server
The mcrypt extension has been abandonware for nearly a decade and was deprecated in PHP 7.1, It has been removed from PHP 7.2. On PHP 7.2 or newer, you can manually install mcrypt from PCEL if you use legacy PHP code that still uses outdated mcrypt extension.

To install PHP mcrypt module on PHP 7.2 in CWP server, do the following.
```
cd /usr/local/src
wget https://pecl.php.net/get/mcrypt-1.0.4.tgz
tar xvf mcrypt-1.0.4.tgz
cd mcrypt-1.0.4
/opt/alt/php72/usr/bin/phpize
./configure -with-php-config=/opt/alt/php72/usr/bin/php-config
make
make install
```
This will install the extension in folder /opt/alt/php72/usr/lib/php/extensions/no-debug-non-zts-20170718/. Copy it to php-fpm extension folder.
```
cp /opt/alt/php72/usr/lib/php/extensions/no-debug-non-zts-20170718/mcrypt.so /opt/alt/php-fpm72/usr/lib/php/extensions/no-debug-non-zts-20170718/
```
Create file mcrypt.ini for both php-fpm and php cli.
```
echo "extension=mcrypt.so" > /opt/alt/php72/usr/php/php.d/mcrypt.ini
echo "extension=mcrypt.so" > /opt/alt/php-fpm72/usr/php/php.d//mcrypt.ini
```
Now you need to restart php-fpm with command
```
systemctl restart php-fpm72
```
Or though CWP admin area
```
CWP Admin > PHP Settings > PHP-FPM Selector
```
Back to CentOS Web Panel (CWP)
January 5, 2022

Install CyberPanel on Ubuntu

To install CyberPanel on Ubuntu, run

apt install -y wget
wget https://cyberpanel.net/install.sh
bash install.sh

Once installed, you can log in to the admin area at

URL: https://SERVER_IP:8090 
Username: admin
Password: password you set during installation

Back to Cyberpanel

December 30, 2021

How to install Engintron on Cpanel Server
Engintron is a Cpanel plugin that allows you to use the Nginx web server as a reverse proxy in front of the Apache webserver used by Cpanel.

To install Engintron on Cpanel Server, run
```
cd /
rm -f engintron.sh
wget --no-check-certificate https://raw.githubusercontent.com/engintron/engintron/master/engintron.sh
bash engintron.sh install
```
Nginx provides micro caching, speeding up websites hosted on the server. Since many of the pages get served from Nginx cache, the server will be able to handle more visitors and reduce server load.
December 29, 2021
How to find MySQL root password in Webuzo
Webuzo Hosting control panel stores MySQL root password in the file /var/webuzo/my.conf

To find MySQL root password on the Webuzo server, run the command
```
cat /var/webuzo/my.conf
```
Back to Webuzo
December 27, 2021

Category: Linux

Install memcached PHP Module

Install memcache module