I have used < file.txt to set a file as the standard input.
But I encountered a new one, <<-'EOF'， in this following command.
$ sudo tee /etc/yum.repos.d/docker.repo <<-'EOF'
[dockerrepo]
name=Docker Repository
baseurl=https://yum.dockerproject.org/repo/main/centos/7/
enabled=1
gpgcheck=1
gpgkey=https://yum.dockerproject.org/gpg
EOF
How should I understand <<-'word'
<< means what? (I know >> file1.txt means appending to the file, file1.txt)
does -'word' means setting word as the ending symbol?
Any links to references/documentations are appreciated~
