today in "omg, i've been doing this for how many years and i'm still learning basic things like this" news. til about quoting heredoc markers to prevent variable expansion.
```shell
❯ cat /tmp/x
#!/bin/sh
foo="bar"
cat<<EOF_0
foo="${foo}"
EOF_0
cat<<"EOF_1"
foo="${foo}"
EOF_1
❯ /tmp/x
foo="bar"
foo="${foo}"
❯
```



