Question

I have a template file(template.txt):

Hello, $x
Hello, $y

I have a script file(script.sh):

#!/bin/bash
$x=linux
$y=unix
# I want to include template.txt as a here-doc

How to include template.txt as a here-doc of script.sh.
So that, when I run script.sh, the output should be:

Hello, linux
Hello, unix

---

Edit:

I think replace is a good command for my job：

$ cat template.txt | replace '$x' linux '$y' unix

A more sophisticated tool:

$ cheetah compile template.tmpl
$ x=linux y=unix python template.py --env

Answer 1

I use this function in one of my projects. It builds an actual here document from the template and then executes it in the current shell using .:

# usage: apply_template /path/to/template.txt
apply_template () {
        (
        trap 'rm -f $tempfile' EXIT
        tempfile=$(mktemp $(pwd)/templateXXXXXX)

        echo 'cat <<END_TEMPLATE' > $tempfile
        cat $1 >> $tempfile
        echo END_TEMPLATE >> $tempfile

        . $tempfile
        )
}