Category: Linux

  • nuster

    nuster

    Configure multiple SSL certificates in nuster

    Back to Reverse Proxy

  • How to Install PHP 5.6 on Oracle Linux 7

    How to Install PHP 5.6 on Oracle Linux 7

    Oracle Linux is a free RHEL based Linux distro. We will install PHP 5.6 on an Oracle Linux 7 server.

    First, enable EPEL repo

    yum install https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm

    Enable Remi repo

    yum install http://rpms.remirepo.net/enterprise/remi-release-7.rpm

    Install yum-utils package

    yum install yum-utils

    Enable remi-php56

    yum-config-manager --enable remi-php56

    Install PHP 5.6 with

    yum install -y php php-bcmath php-cli php-common php-devel php-gd \
    php-imap php-intl php-json php-ldap php-lz4 php-mbstring php-mysqlnd \
    php-soap php-intl php-opcache php-xml php-pdo

    This will only install the CLI version of PHP 5.6. To make Apache work with PHP 5.6, install

    yum install php-pecl-http.x86_64

    This will create file /etc/httpd/conf.d/php.conf, that enable PHP module in Apache.

    Restart apache webserver

    systemctl restart httpd

    Now Apache will be able to serve PHP files.

  • Install Jenkins on Ubuntu

    Install Jenkins on Ubuntu

    Jenkins is an open source automation server. It helps automate the parts of software development related to building, testing, and deploying, facilitating continuous integration and continuous delivery.

    Jenkins is a Java Application. So you need to install JRE (Java Runtime Environment). Install it with

    sudo apt-get install default-jre

    You can find instructions for installing Jenkins on Debian/Ubuntu at

    https://pkg.jenkins.io/debian-stable/

    Install Jenkins

    wget -q -O - https://pkg.jenkins.io/debian-stable/jenkins.io.key | sudo apt-key add -
sudo sh -c 'echo deb https://pkg.jenkins.io/debian-stable binary/ > /etc/apt/sources.list.d/jenkins.list'
sudo apt-get update
sudo apt-get install jenkins

    Enable Jenkins to start on boot 

    sudo systemctl enable jenkins

    Start Jenkins

    sudo systemctl start jenkins

    To check status

    sudo systemctl status jenkins

    You can verify Jenkins running on port 8080 with command

    root@jenkins:~# netstat -lntp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 127.0.0.53:53           0.0.0.0:*               LISTEN      186/systemd-resolve 
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      256/sshd: /usr/sbin 
tcp6       0      0 :::22                   :::*                    LISTEN      256/sshd: /usr/sbin 
tcp6       0      0 :::8080                 :::*                    LISTEN      4774/java           
root@jenkins:~#

    To find the initial password, run the command

    cat /var/lib/jenkins/secrets/initialAdminPassword
  • Install Tomcat on CentOS 7

    Install Tomcat on CentOS 7

    Apache Tomcat is an open source implementation of the Java Servlet and Java Server Pages. To install Apache Tomcat on CentOS 7, run

    yum install tomcat

    To enable tomcat start on boot

    systemctl enable tomcat

    You can manage tomcat with

    systemctl stop tomcat
systemctl start tomcat
systemctl status tomcat
systemctl restart tomcat

    To see the ports used by tomcat

    [root@tomcat ~]# netstat -lntp| grep java
tcp6       0      0 127.0.0.1:8005          :::*                    LISTEN      31423/java          
tcp6       0      0 :::8009                 :::*                    LISTEN      31423/java          
tcp6       0      0 :::8080                 :::*                    LISTEN      31423/java          
[root@tomcat ~]#

    webapps are stored in the directory

    /var/lib/tomcat/webapps

    Create the default page with

    mkdir /var/lib/tomcat/webapps/ROOT
echo "Hello Cat" > /var/lib/tomcat/webapps/ROOT/index.html

    Tomcat web server can be accessed using

    http://your-server-ip:8080

    To open 8080 port on the firewall, use commands

    firewall-cmd --permanent --zone=public --add-port=8080/tcp
firewall-cmd --reload

    Tomcat configurations are available in the directory.

    /etc/tomcat/

    Install tomcat Manager

    To install the Tomcat manager GUI application, run

    yum install tomcat-admin-webapps.noarch -y

    To create user, edit file

    vi /etc/tomcat/tomcat-users.xml

    Inside ““, add

    USER_NAME_HERE and PW_HERE – replace with the username and password you need.

    Restart tomcat to activate Tomcat Manager GUI.

    systemctl restart tomcat

    To access GUI, go to

    http://your-server-ip-here:8080/manager/
  • How to change Node Exporter port

    How to change Node Exporter port

    Node Exporter by default uses port 9100. You may need to use another port for Node Exporter if port 9100 is already used by another program on your server. On an OVH VPS, noderig was running in port 9100 and Node Exporter failed to start. To fix the issue, i had to run Node Exporter on a different port.

    To change the Node Exporter port, edit the file

    /etc/systemd/system/node_exporter.service

    Find line

    ExecStart=/usr/local/bin/node_exporter

    Replace it with

    ExecStart=/usr/local/bin/node_exporter --web.listen-address=:9101

    In the above line, 9101 is the new Node Exporter port. You can change it to any other port as required.

    Here is the complete code

    root@ns568267:~# cat /etc/systemd/system/node_exporter.service
[Unit]
Description=Node Exporter
Wants=network-online.target
After=network-online.target

[Service]
User=node_exporter
Group=node_exporter
Type=simple
ExecStart=/usr/local/bin/node_exporter --web.listen-address=:9101

[Install]
WantedBy=multi-user.target
root@ns568267:~#

    Reload systemd

    systemctl daemon-reload

    Restart node exporter

    systemctl start node_exporter

    You can verify node_exporter is running with the command

    root@ns568267:~# netstat -lntp | grep node_
tcp6       0      0 :::9101                 :::*                    LISTEN      15630/node_exporter 
root@ns568267:~#
  • top

    top

    top command is used to see current system resource usage

    To show the current process

    top -n 1 -b

    Top sorted by memory

    top -b -n 1 -o %MEM | sort -nk 6

    Delay 3 second

    top -cd3

    Back to Linux Commands

  • ack show the matched files name only

    ack show the matched files name only

    ack is a command-line utility written in Perl for searching strings inside files. By default when you search, it shows you the file name along with the matching content of the file. Sometimes you may only want to list file names that match your search. This can be done with -l option

    ack -l "search string here"

    Example

    ack list files

    See ack

  • Install .NET SDK on Ubuntu 20.04

    Install .NET SDK on Ubuntu 20.04

    Microsoft .NET SDK and Run time now available for Linux. To install .NET SDK and runtime on Ubuntu 20.04, follow the instructions below

    Run the following commands as user root. If you are logged in as a normal user, use the command “sudo su” to become user root.

    wget https://packages.microsoft.com/config/ubuntu/20.04/packages-microsoft-prod.deb -O packages-microsoft-prod.deb
dpkg -i packages-microsoft-prod.deb
rm packages-microsoft-prod.deb

    Update the repo and install apt-transport-https

    apt-get update
apt-get install -y apt-transport-https

    Search for available dotnet-sdk versions

    apt-cache search dotnet-sdk

    apt search dotnet-sdk

    On Ubuntu 20.04, Microsoft provides .NET SDK version 2.1, 3.1, and 5. Let’s install version 5.

    apt-get install -y dotnet-sdk-5.0

    To find the version of .NET SDK, run

    dotnet --version

    Find dotnet version in Ubuntu

    You can find .NET SDK and runtime available with commands

    dotnet --list-sdks
dotnet --list-runtimes
  • Enable/Disable Nextcloud Maintenance Mode

    Enable/Disable Nextcloud Maintenance Mode

    Maintenance mode is useful when you are making changes to your nextcloud installation like a software upgrade.

    To enable maintenance mode, run the command

    php7.3 occ maintenance:mode --on

    To disable maintenance mode, run

    php7.3 occ maintenance:mode --off

    Example

    www-data@mail:/www/nextcloud$ php occ maintenance:mode --off
Maintenance mode disabled
www-data@mail:/www/nextcloud$

    See Nextcloud

  • Module php-imagick in this instance has no SVG support

    Module php-imagick in this instance has no SVG support

    On Ubuntu server running Nextcloud, I got the following warning in Nextcloud

    Module php-imagick in this instance has no SVG support. For better compatibility it is recommended to install it.

    To fix this warning, install libmagickcore-6.q16-6-extra package with the command

    apt-get install libmagickcore-6.q16-6-extra

    See Nextcloud

  • chattr: Operation not supported while reading flags

    chattr: Operation not supported while reading flags

    When making a file immutable with chattr command, I get the following error

    [root@vps784847 vhosts]# chattr +i serverok.in.conf 
chattr: Operation not supported while reading flags on serverok.in.conf
[root@vps784847 vhosts]#

    The error was due to the file I was trying to chattr being a symlink, not a real file.

    [root@vps784847 vhosts]# ls -la
total 0
drwxr-xr-x. 2 root root  31 Oct 27 08:11 .
drwxr-xr-x. 7 root root 131 Jun  1 02:03 ..
lrwxrwxrwx. 1 root root  51 Jul 24 12:39 serverok.in.conf -> /var/www/vhosts/system/serverok.in/conf/nginx.conf
[root@vps784847 vhosts]#

    To fix the error, chattr the actual file.

    chattr +i /var/www/vhosts/system/serverok.in/conf/nginx.conf

    Back to Linux Commands

  • Checking NVMe Disk

    Checking NVMe Disk

    You can use nvme-cli to check your NVMe disks. To install nvme-cli, run

    On Ubuntu/Debian

    sudo apt-get install -y nvme-cli

    On RHEL

    sudo yum install nvme-cli

    To list of NVMe drives, use

    nvme list

    Example

    [root@server52 ~]# nvme list
Node             SN                   Model                                    Namespace Usage                      Format           FW Rev  
---------------- -------------------- ---------------------------------------- --------- -------------------------- ---------------- --------
/dev/nvme0n1     S439NA0N900171       SAMSUNG MZQLB1T9HAJR-00007               1         531.97  GB /   1.92  TB    512   B +  0 B   EDA5402Q
/dev/nvme1n1     S439NA0N900057       SAMSUNG MZQLB1T9HAJR-00007               1         532.00  GB /   1.92  TB    512   B +  0 B   EDA5402Q
[root@server52 ~]#

    To find smart data, run

    nvme smart-log DEVICE_NAME_HERE

    Example

    [root@server52 ~]# nvme smart-log /dev/nvme0n1
Smart Log for NVME device:nvme0n1 namespace-id:ffffffff
critical_warning                    : 0
temperature                         : 39 C
available_spare                     : 100%
available_spare_threshold           : 10%
percentage_used                     : 0%
data_units_read                     : 130,334,241
data_units_written                  : 69,361,921
host_read_commands                  : 866,547,209
host_write_commands                 : 710,448,251
controller_busy_time                : 998
power_cycles                        : 88
power_on_hours                      : 5,464
unsafe_shutdowns                    : 83
media_errors                        : 0
num_err_log_entries                 : 0
Warning Temperature Time            : 0
Critical Composite Temperature Time : 0
Temperature Sensor 1                : 39 C
Temperature Sensor 2                : 43 C
Temperature Sensor 3                : 47 C
Thermal Management T1 Trans Count   : 0
Thermal Management T2 Trans Count   : 0
Thermal Management T1 Total Time    : 0
Thermal Management T2 Total Time    : 0
[root@server52 ~]#

    To see the NVMe error log

    nvme error-log	DEVICE_NAME_HERE