94 lines
2.2 KiB
Bash
94 lines
2.2 KiB
Bash
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#!/bin/bash
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# Replaces all {{VAR}} by the $VAR value in a template file and outputs it
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# Use with -h to output all variables
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if [[ ! -f "$1" ]]; then
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echo "Usage: VAR=value $0 template" >&2
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exit 1
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fi
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template="$1"
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vars=$(grep -oE '\{\{\s*[A-Za-z0-9_]+\s*\}\}' "$template" | sort | uniq | sed -e 's/^{{//' -e 's/}}$//')
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if [[ -z "$vars" ]]; then
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echo "Warning: No variable was found in $template, syntax is {{VAR}}" >&2
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fi
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var_value() {
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var="${1}"
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eval echo \$"${var}"
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}
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##
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# Escape custom characters in a string
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# Example: escape "ab'\c" '\' "'" ===> ab\'\\c
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#
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function escape_chars() {
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local content="${1}"
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shift
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for char in "$@"; do
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content="${content//${char}/\\${char}}"
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done
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echo "${content}"
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}
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function echo_var() {
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local var="${1}"
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local content="${2}"
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local escaped="$(escape_chars "${content}" "\\" '"')"
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echo "${var}=\"${escaped}\""
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}
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declare -a replaces
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replaces=()
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# Reads default values defined as {{VAR=value}} and delete those lines
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# There are evaluated, so you can do {{PATH=$HOME}} or {{PATH=`pwd`}}
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# You can even reference variables defined in the template before
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defaults=$(grep -oE '^\{\{[A-Za-z0-9_]+=.+\}\}$' "${template}" | sed -e 's/^{{//' -e 's/}}$//')
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IFS=$'\n'
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for default in $defaults; do
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var=$(echo "${default}" | grep -oE "^[A-Za-z0-9_]+")
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current="$(var_value "${var}")"
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# Replace only if var is not set
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if [[ -n "$current" ]]; then
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eval "$(echo_var "${var}" "${current}")"
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else
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eval "${default}"
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fi
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# remove define line
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replaces+=("-e")
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replaces+=("/^{{${var}=/d")
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vars="${vars} ${var}"
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done
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vars="$(echo "${vars}" | tr " " "\n" | sort | uniq)"
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if [[ "$2" = "-h" ]]; then
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for var in $vars; do
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value="$(var_value "${var}")"
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echo_var "${var}" "${value}"
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done
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exit 0
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fi
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# Replace all {{VAR}} by $VAR value
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for var in $vars; do
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value="$(var_value "${var}")"
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if [[ -z "$value" ]]; then
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echo "Warning: $var is not defined and no default is set, replacing by empty" >&2
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fi
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# Escape slashes
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value="$(escape_chars "${value}" "\\" '/' ' ')";
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replaces+=("-e")
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replaces+=("s/{{\s*${var}\s*}}/${value}/g")
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done
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sed "${replaces[@]}" "${template}"
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