Add support for ESH

yadm

@@ -45,6 +45,7 @@ GIT_CRYPT_PROGRAM="git-crypt"
 TRANSCRYPT_PROGRAM="transcrypt"
 J2CLI_PROGRAM="j2"
 ENVTPL_PROGRAM="envtpl"
+ESH_PROGRAM="esh"
 LSB_RELEASE_PROGRAM="lsb_release"
 
 OS_RELEASE="/etc/os-release"
@@ -299,6 +300,8 @@ function choose_template_cmd() {
 
   if [ "$kind" = "default" ] || [ "$kind" = "" ] && awk_available; then
     echo "template_default"
+  elif [ "$kind" = "esh" ] && esh_available; then
+    echo "template_esh"
   elif [ "$kind" = "j2cli" ] || [ "$kind" = "j2" ] && j2cli_available; then
     echo "template_j2cli"
   elif [ "$kind" = "envtpl" ] || [ "$kind" = "j2" ] && envtpl_available; then
@@ -407,6 +410,22 @@ function template_envtpl() {
   [ -f "$temp_file" ] && mv -f "$temp_file" "$output"
 }
 
+function template_esh() {
+  input="$1"
+  output="$2"
+  temp_file="${output}.$$.$RANDOM"
+
+  "$ESH_PROGRAM" -o "$temp_file" "$input" \
+  YADM_CLASS="$local_class"   \
+  YADM_OS="$local_system"     \
+  YADM_HOSTNAME="$local_host" \
+  YADM_USER="$local_user"     \
+  YADM_DISTRO="$local_distro" \
+  YADM_SOURCE="$input"
+
+  [ -f "$temp_file" ] && mv -f "$temp_file" "$output"
+}
+
 # ****** yadm Commands ******
 
 function alt() {
@@ -1936,6 +1955,10 @@ function envtpl_available() {
   command -v "$ENVTPL_PROGRAM" &> /dev/null && return
   return 1
 }
+function esh_available() {
+  command -v "$ESH_PROGRAM" &> /dev/null && return
+  return 1
+}
 function readlink_available() {
   command -v "readlink" &> /dev/null && return
   return 1