An "envsubst" alternative for replacing env variables in NGinX site configurations (for using it with Docker)

gistfile1.txt

#!/bin/bash

# NOTE: Brackets are not supported and '$' in values will break the script.

mkdir /etc/nginx/sites-enabled 2> /dev/null
for file in /etc/nginx/sites-available/*.conf
do
    TPL=$(cat $file)
    for row in $(env)
    do
        IFS="="
        read key val <<< "$row"
        if [[ $val == tcp://* ]]
        then
          valhttp=$(echo -n $val | sed 's#^tcp://#http://#')
          TPL=$(echo -n $TPL | sed "s\$\\\$$key\_HTTP\$$valhttp\$")
        fi
        TPL=$(echo -n $TPL | sed "s\$\\\$$key\$$val\$")
    done
    echo -n $TPL > "/etc/nginx/sites-enabled/$(basename $file)"
done

nginx -g "daemon off;"