Error - Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable) or Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?

Error -  Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?

or -  Error - Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable)

You May experience error above during execution of apt command in Ubuntu. 

root@US16:~# apt install apache2
E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable)
E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?

Solution: -  Previous apt command might be interrupted in middle somehow and it keeps the lock file exist. remove lock file using the command below.

root@US16:~# mv /var/lib/dpkg/lock /var/lib/dpkg/lock-bak

Now retry command to install package

root@US16:~# apt install apache2
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
  apache2-bin apache2-data apache2-utils libapr1 libaprutil1 libaprutil1-dbd-sqlite3 libaprutil1-ldap liblua5.1-0 ssl-cert
Suggested packages:
  www-browser apache2-doc apache2-suexec-pristine | apache2-suexec-custom openssl-blacklist
The following NEW packages will be installed:
  apache2 apache2-bin apache2-data apache2-utils libapr1 libaprutil1 libaprutil1-dbd-sqlite3 libaprutil1-ldap liblua5.1-0 ssl-cert
0 upgraded, 10 newly installed, 0 to remove and 189 not upgraded.
Need to get 1,557 kB of archives.
After this operation, 6,428 kB of additional disk space will be used.
Do you want to continue? [Y/n] y

Command executed successfully with error, Issue solved

!!!!That's ALL!!!!