--- convert/convert_script.lua	2016-03-18 19:30:49.675401969 +0100
+++ convert_script.lua	2016-03-19 01:18:00.801897043 +0100
@@ -3,6 +3,10 @@
 local opt = require 'mp.options'
 local utils = require 'mp.utils'
 
+local NOTIFY_CMD = "notify-send"
+local YAD_CMD = "yad"
+local MKVMERGE_CMD = "mkvmerge"
+
 -- default options, convert_script.conf is read
 local options = {
     bitrate_multiplier = 0.975,			-- to make sure the file won’t go over the target file size, set it to 1 if you don’t care
@@ -354,9 +358,9 @@
     if ovc == "gif" then
         full_command = full_command .. ' --vf-add=lavfi=graph=\\"framestep=' .. framestep .. '\\" && convert ' 
         .. tmpfolder .. '/*.png -set delay ' .. delay .. ' -loop 0 -fuzz ' .. fuzz .. '% ' .. dither .. ' -layers optimize '
-        .. full_output_path .. ' && rm -rf ' .. tmpfolder .. ' && notify-send "Gif done") & disown'
+        .. full_output_path .. ' && rm -rf ' .. tmpfolder .. ' && ' .. NOTIFY_CMD .. ' "Gif done") & disown'
     else
-        full_command = full_command .. ' && notify-send "Encoding done"; mkvpropedit '
+        full_command = full_command .. ' && ' .. NOTIFY_CMD .. ' "Encoding done"; mkvpropedit '
         .. full_output_path .. ' -s title="' .. metadata_title .. '") & disown'
     end
     
@@ -409,7 +413,7 @@
     sep = ",+"
     
     if enc then
-        local command = "mkvmerge '" .. video .. "' " .. mkvmerge_parts .. " -o " .. full_output_path
+        local command = MKVMERGE_CMD .. " '" .. video .. "' " .. mkvmerge_parts .. " -o " .. full_output_path
         msg.info(command)
         os.execute(command)
         clear()
@@ -508,7 +512,7 @@
     end
     
     
-    local yad_command = [[LC_NUMERIC=C yad --title="Convert Script" --center --form --fixed --always-print-result \
+    local yad_command = [[LC_NUMERIC=C ]] .. YAD_CMD .. [[ --title="Convert Script" --center --form --fixed --always-print-result \
     --name "convert script" --class "Convert Script" --field="Resize to height:NUM" "]] .. scale_sav		--yad_table 1
     .. [[" --field="Resize to width instead:CHK" ]] .. resize_to_width_instead .. " "				--yad_table 2
     if options.legacy_yad then
@@ -543,7 +547,7 @@
     yad_command = yad_command .. [[ --button="Crop:1" --button="gtk-cancel:2" --button="gtk-ok:0"; ret=$? && echo $ret]]
     
     if gif_dialog then
-        yad_command = [[echo $(LC_NUMERIC=C yad --title="Gif settings" --name "convert script" --class "Convert Script" \
+        yad_command = [[echo $(LC_NUMERIC=C ]] .. YAD_CMD .. [[ --title="Gif settings" --name "convert script" --class "Convert Script" \
         --center --form --always-print-result --separator="…" \
         --field="Fuzz Factor:NUM" '1!0..100!0.5!1' \
         --field="Framestep:NUM" '3!1..3!1' \