How to define a multiple page ranges for pdftk with a bash variable

I'm using Arch linux, Openbox window manager, and bash. Everything is up to date with the latest versions. Can anyone tell me why I can't get the "$page_range" variable to show up within pdftk when I specify a couple of page ranges as 3-5 7-9? When I specify only one page range 3-5 in my yad pop-up box everything works as it should. pdftk does allow more than one page range to be defined within the command. Indeed when I type the command out on the command line without using bash variables within it, pdftk works as expected taking the page ranges 3-5 7-9. Just not when I contain this value within the variable "$page_range". All I want to do is extract page ranges 3-5 and 7-9 from file /home/$USER/my_file.pdf into another pdf file using the variable $page_range to define my ranges. Here is my simple script. #!/bin/bash # collect the values with yad extract_values=$(yad --form --width=200 \ --title="Enter the page ranges you wish to extract" \ --text="\n\n Enter the page ranges you wish to extract\n as eg 301-302\n or 301-302 305-306\n for grouping" \ --field="Page range":text "11-13 21-23" \ --button="Cancel!gtk-close":2 \ --button="Edit script":1 \ --button="Submit":0) # strip out the values from the string page_range=$(echo $extract_values | cut -d '|' -f 1) echo $page_range # produce a unique file extender page_range_slugify="$(echo "$page_range" | sed 's/ /_/g')" echo;echo $page_range_slugify echo # specify the filename f=/home/$USER/my_file.pdf # get path and file name without pdf extension fz="${f%.*}" # check everything is as it should be yad --text="\n page range = $page_range\n page_range_slugify = $page_range_slugify\n file + path without file extension = $fz\n\n" # below works only for one range but will not expand for two page ranges pdftk "$f" cat "$page_range" output "$fz"_"$page_range_slugify".pdf # below takes one range only as above #pdftk "$f" cat "$(printf %s "$page_range")" output "$fz"_"$page_range_slugify".pdf # below takes both ranges when ranges are directly placed within the command #pdftk "$f" cat 3-5 7-9 output "$fz"_"$page_range_slugify".pdf