Lalit Mohan Jaimini – Lalit Mohan Jaimini

Ubuntu apt-get problem “KEYEXPIRED: The following signatures were invalid”

apt-get update Problem

Ign:11 https://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/3.6 InRelease
Hit:12 https://repos.sonar.digitalocean.com/apt main InRelease
Hit:13 https://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/3.6 Release
Err:17 https://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/3.6 Release.gpg
The following signatures were invalid: KEYEXPIRED 1544811256
Fetched 1930 kB in 3s (601 kB/s)
Reading package lists… Done

W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/3.6 Release: The following signatures were invalid: KEYEXPIRED 1544811256

W: Failed to fetch https://repo.mongodb.org/apt/ubuntu/dists/xenial/mongodb-org/3.6/Release.gpg The following signatures were invalid: KEYEXPIRED 1544811256
W: Some index files failed to download. They have been ignored, or old ones used instead.

Step 1: Find the Expired key
sudo apt-key list | grep -A 1 expired

Step 2: Renew the Expired key
sudo apt-key adv –keyserver hkp://keyserver.ubuntu.com:80 –recv-keys
, the one you copied from above

Step 3:
sudo apt-get update

Remove the git branch from the local and server side

Delete branch from remote location –
git push -d remote-name branch-name

Delete branch from localhost –
git branch -D branch-name git branch -d branch-name

Allow ufw firewall in ubuntu

enable firewall - sudo ufw enable
reload firewall - sudo ufw reload
disable firewall - sudo ufw disable
allow port ya service - sudo ufw allow port/service-name 
(like - sudo ufw allow ssh 
or 
sudo ufw allow 22
or 
sudo ufw allow from sourceip to any port 22) 
allow rule delete - sudo ufw delete allow port/service-name 
(like - sudo ufw delete allow ssh 
or 
sudo ufw delete allow 22
or
sudo ufw delete allow from sourceip to any port 22)

install ffmpeg in ubuntu

sudo add-apt-repository ppa:jonathonf/ffmpeg-4
sudo apt-get update
sudo apt-get install ffmpeg

Disable apache server status in ubuntu

sudo a2dismod status
sudo systemctl restart apache2.service

Use of Hindi (unicode) character from request parameter in java

String str = request.getParameter("sentence");
System.out.println("before convert - " + str);
str = new String(request.getParameter("sentence").getBytes("ISO-8859-1"),"UTF-8");
System.out.println("after convert - " + str);

Round a double to any decimal places in java

int n = 2;

round(xxxx.xxxxx, n); // Return xxxx.xx

Create username password for apache tomcat user

sudo vi /opt/tomcat/conf/tomcat-users.xml

<role rolename="manager-gui"/>
     <user password="" roles="manager-script,admin" username=""/>
     <user password="" roles="manager-gui,manager-script,admin" username=""/>

then restart tomcat service
sudo systemctl restart tomcat.service

Failed to connect http://changelogs.ubuntu.com/meta-release

sudo rm /var/lib/ubuntu-release-upgrader/release-upgrade-available
sudo /usr/lib/ubuntu-release-upgrader/release-upgrade-motd

Switch to another user in linux

su username