Shell expansion with heredoc

Question

How does one for subshell expansion in heredoc for all command?

eg:

file=report_$(date +%Y%m%d)
cat <<EOF > $file
    date
    hostname
    echo 'End of Report'
EOF

such that all the commands are evaluated?

I am aware

file=report_$(date +%Y%m%d)
cat <<EOF > $file
    $(date))
    $(hostname)
    $(echo 'End of Report')
EOF

would work, but is there a way to specify subshell by default?

Answer 1

You could use sh (or bash) as the command instead of cat; that will actually run it as shell script:

sh <<EOF > $file
    date
    hostname
    echo 'End of Report'
EOF