--recursive           initialize submodules in the clone
    --recurse-submodules  initialize submodules in the clone
    --template <template-directory>
                          directory from which templates will be used
    --reference <repo>    reference repository
    -o, --origin <name>   use <name> instead of 'origin' to track upstream
    -b, --branch <branch>
                          checkout <branch> instead of the remote's HEAD
    -u, --upload-pack <path>
                          path to git-upload-pack on the remote
    --depth <depth>       create a shallow clone of that depth
    --single-branch       clone only one branch, HEAD or --branch
    --separate-git-dir <gitdir>
                          separate git dir from working tree
    -c, --config <key=value>
                          set config inside the new repository

[root@karl home]# service nginx stop
Redirecting to /bin/systemctl stop  nginx.service

[root@karl home]#
[root@karl home]# # Install Let's Encrypt
[root@karl home]# cd /opt/letsencrypt
-bash: cd: /opt/letsencrypt: No such file or directory
[root@karl home]# ./letsencrypt-auto certonly --standalone