catch {exec pdfgrep > /dev/null &} res if {![string is integer -strict $res]} { gnocl::dialog \ -title "pdfSeach" \ -text "<b>ERROR!\n\n</b> <b>pdfgrep</b> not present on this computer!\n\nInstall using:\n\n<b>sudo apt install pdfgrep</b>\n\n" -type error return -code error }