EOF

Examples of cat <<EOF syntax usage in Bash:

#!/bin/bash

docker build -t willrstern/test-node .

docker push willrstern/test-node

ssh root@162.243.27.75 << 'EOF'

    for i in `seq 1 3`

    do

      docker -H :4000 build --build-arg="affinity:container==~web$i" --pull - <<< "FROM willrstern/test-node"

      docker -H :4000 stop web$i || true

      docker -H :4000 rm web$i || true

      docker -H :4000 run -d --restart always --net apps --name web$i \

        -e constraint:type==apps \

        -e SERVICE_VIRTUAL_HOST=test.com \

        -e SERVICE_NAME=web \

        -e SERVICE_TAGS=nginx:production \

        -e SERVICE_PORT=3000 \

        willrstern/test-node

    done

EOF

1. Assign multi-line string to a shell variable

$ sql=$(cat <<EOF
SELECT foo, bar FROM db
WHERE foo='baz'
EOF
)

The $sql variable now holds the new-line characters too. You can verify with echo -e "$sql".

2. Pass multi-line string to a file in Bash

$ cat <<EOF > print.sh
#!/bin/bash
echo \$PWD
echo $PWD
EOF

The print.sh file now contains:

#!/bin/bash
echo $PWD
echo /home/user

3. Pass multi-line string to a pipe in Bash

$ cat <<EOF | grep 'b' | tee b.txt
foo
bar
baz
EOF