Added -o, --vars-optional args (variables no longer required)

README.md

@@ -10,9 +10,37 @@ Supports default values by writting `{{VAR=value}}` in the template.
 
 Sébastien Lavoie <github@lavoie.sl>
 
-See http://blog.lavoie.sl/2012/11/simple-templating-system-using-bash.html for other details
+Johan Haleby
+
+See http://code.haleby.se/2015/11/20/simple-templating-engine-in-bash/  and http://blog.lavoie.sl/2012/11/simple-templating-system-using-bash.html for more details
+
+## Installation
+
+To install templater in linux type:
+
+    sudo curl -L https://raw.githubusercontent.com/johanhaleby/bash-templater/master/templater.sh -o /usr/local/bin/templater
+    sudo chmod +x /usr/local/bin/templater
 
 ## Usage
+
+```bash
+VAR=value templater template
+```
+
+Read variables from file:
+
+```bash
+templater template -f variables.txt
+```
+
+e.g.:
+```bash
+# variables.txt
+# The author
+AUTHOR=Johan
+# The version
+VERSION=1.2.3
+```
 
 ```sh
 # Passing arguments directly
@@ -23,6 +51,12 @@ VAR=value templater.sh template
 # Parentheses are important for not polluting the current shell
 (set -a && . /tmp/foo && templater.sh template)
 
+# Passing variables to template via a file
+templater.sh template -f variables.txt
+
+# Squelching all warning messages
+templater.sh template -s
+
 # A variant that does NOT pass current env variables to the templater
 sh -c "set -a && . /tmp/foo && templater.sh template"
 ```

templater.sh

@@ -1,19 +1,133 @@
 #!/bin/bash
+#
+# Very simple templating system that replaces {{VAR}} by the value of $VAR.
+# Supports default values by writting {{VAR=value}} in the template.
+#
+# Copyright (c) 2017 Sébastien Lavoie
+# Copyright (c) 2017 Johan Haleby
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+#
+# See: https://github.com/johanhaleby/bash-templater
+# Version: https://github.com/johanhaleby/bash-templater/commit/5ac655d554238ac70b08ee4361d699ea9954c941
+
 # Replaces all {{VAR}} by the $VAR value in a template file and outputs it
-# Use with -h to output all variables
 
-if [[ ! -f "$1" ]]; then
-    echo "Usage: VAR=value $0 template" >&2
+readonly PROGNAME=$(basename $0)
+
+config_file="<none>"
+print_only="false"
+silent="false"
+
+usage="${PROGNAME} [-h] [-d] [-f] [-s] [-o] -- 
+
+where:
+    -h, --help
+        Show this help text
+    -p, --print
+        Don't do anything, just print the result of the variable expansion(s)
+    -f, --file
+        Specify a file to read variables from
+    -s, --silent
+        Don't print warning messages (for example if no variables are found)
+    -o, --vars-optional
+        Allow for no variables to be present (simply returns the template as is)
+
+examples:
+    VAR1=Something VAR2=1.2.3 ${PROGNAME} test.txt 
+    ${PROGNAME} test.txt -f my-variables.txt
+    ${PROGNAME} test.txt -f my-variables.txt > new-test.txt"
+
+if [ $# -eq 0 ]; then
+  echo "$usage"
+  exit 1    
+fi
+
+if [[ ! -f "${1}" ]]; then
+    echo "You need to specify a template file" >&2
+    echo "$usage"
     exit 1
 fi
 
-template="$1"
-vars=$(grep -oE '\{\{\s*[A-Za-z0-9_]+\s*\}\}' "$template" | sort | uniq | sed -e 's/^{{//' -e 's/}}$//')
+template="${1}"
+
+if [ "$#" -ne 0 ]; then
+    while [ "$#" -gt 0 ]
+    do
+        case "$1" in
+        -h|--help)
+            echo "$usage"
+            exit 0
+            ;;        
+        -p|--print)
+            print_only="true"
+            ;;
+        -f|--file)
+            config_file="$2"
+            ;;
+        -s|--silent)
+            silent="true"
+            ;;
+        -o|--vars-optional)
+            vars_optional="true"
+            ;;
+        --)
+            break
+            ;;
+        -*)
+            echo "Invalid option '$1'. Use --help to see the valid options" >&2
+            exit 1
+            ;;
+        # an option argument, continue
+        *)  ;;
+        esac
+        shift
+    done
+fi
+
+vars=$(grep -oE '\{\{[A-Za-z0-9_]+\}\}' "${template}" | sort | uniq | sed -e 's/^{{//' -e 's/}}$//')
 
 if [[ -z "$vars" ]]; then
-    echo "Warning: No variable was found in $template, syntax is {{VAR}}" >&2
+    if [ "$vars_optional" == "true" ]; then
+        if [ "$print_only" == "false" ]; then
+            cat $template
+        fi
+        exit 0
+    else
+        if [ "$silent" == "false" ]; then
+            echo "Warning: No variable was found in ${template}, syntax is {{VAR}}" >&2
+        fi
+        exit 1
+    fi
 fi
 
+# Load variables from file if needed
+if [ "${config_file}" != "<none>" ]; then
+    if [[ ! -f "${config_file}" ]]; then
+      echo "The file ${config_file} does not exists" >&2
+      echo "$usage"      
+      exit 1
+    fi
+
+    source "${config_file}"
+fi    
+
 var_value() {
     var="${1}"
     eval echo \$"${var}"
@@ -48,8 +162,7 @@ replaces=()
 # Reads default values defined as {{VAR=value}} and delete those lines
 # There are evaluated, so you can do {{PATH=$HOME}} or {{PATH=`pwd`}}
 # You can even reference variables defined in the template before
-defaults=$(grep -oE '^\{\{[A-Za-z0-9_]+=.+\}\}$' "${template}" | sed -e 's/^{{//' -e 's/}}$//')
-IFS=$'\n'
+defaults=$(grep -oE '^\{\{[A-Za-z0-9_]+=.+\}\}' "${template}" | sed -e 's/^{{//' -e 's/}}$//')
 for default in $defaults; do
     var=$(echo "${default}" | grep -oE "^[A-Za-z0-9_]+")
     current="$(var_value "${var}")"
@@ -69,7 +182,7 @@ done
 
 vars="$(echo "${vars}" | tr " " "\n" | sort | uniq)"
 
-if [[ "$2" = "-h" ]]; then
+if [[ "$print_only" == "true" ]]; then
     for var in $vars; do
         value="$(var_value "${var}")"
         echo_var "${var}" "${value}"
@@ -79,15 +192,17 @@ fi
 
 # Replace all {{VAR}} by $VAR value
 for var in $vars; do
-    value="$(var_value "${var}")"
+    value=$(var_value $var | sed -e "s;\&;\\\&;g" -e "s;\ ;\\\ ;g") # '&' and <space> is escaped
     if [[ -z "$value" ]]; then
-        echo "Warning: $var is not defined and no default is set, replacing by empty" >&2
+        if [ $silent == "false" ]; then
+            echo "Warning: $var is not defined and no default is set, replacing by empty" >&2
+        fi
     fi
 
     # Escape slashes
-    value="$(escape_chars "${value}" "\\" '/' ' ')";
-    replaces+=("-e")
-    replaces+=("s/{{\s*${var}\s*}}/${value}/g")
+    value=$(echo "$value" | sed 's/\//\\\//g');
+    replaces="-e 's/{{$var}}/${value}/g' $replaces"    
 done
 
-sed "${replaces[@]}" "${template}"
+escaped_template_path=$(echo $template | sed 's/ /\\ /g')
+eval sed $replaces "$escaped_template_path"