When using the docker container, sometimes not installed inside vim, suggesting that when the knock vim command: vim: command not found, this time on the need to install vim, but when you knock apt-get install vim command prompt:
This is when you need to knock: apt-get update
The role of the command is: index of the source and /etc/apt/sources.list.d listed in synchronization /etc/apt/sources.list, in order to get the latest software packages.
Etc. After the update is completed and then knock command: apt-get install vim command to