install gitlab-runner on linux (ubuntu x86_64)

$ uname -a
Linux shlee-VirtualBox 4.15.0-29-generic #31-Ubuntu SMP Tue Jul 17 15:39:52 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

// Simply download one of the binaries for your system
$ sudo wget -O /usr/local/bin/gitlab-runner https://gitlab-runner-downloads.s3.amazonaws.com/latest/binaries/gitlab-runner-linux-amd64
...
/usr/local/bin/gitl 100%[++++++++++++++++++=>]  29.28M   331KB/s    in 10s
2019-02-21 06:50:17 (210 KB/s) - ‘/usr/local/bin/gitlab-runner’ saved [30703328/30703328]

// Give it permissions to execute
$ sudo chmod +x /usr/local/bin/gitlab-runner

// Create a GitLab CI user:
$ sudo useradd --comment 'Gitlab Runner' --create-home gitlab-runner --shell /bin/bash

//Install and run as service
$ sudo gitlab-runner install --user=gitlab-runner --working-directory=/home/gitlab-runner
Runtime platform                                    arch=amd64 os=linux pid=24039 revision=4745a6f3 version=11.8.0
$ sudo gitlab-runner start
Runtime platform                                    arch=amd64 os=linux pid=24420 revision=4745a6f3 version=11.8.0

// Stop the service 
$ sudo gitlab-runner stop