qdelaunay: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/qdelaunay - from package: qhull

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/qdelaunay - from package: qhull-bin

You may install the required package with command apt-get install {package}

Error in other languages:
qdelaunay: bevel nie gevind nie
qdelaunay: comandă negăsită
qdelaunay: comando não encontrado
qdelaunay: commande introuvable
qdelaunay: command not found
qdelaunay: käsku ei ole
qdelaunay: không tìm thấy lệnh
qdelaunay: komanda nerasta
qdelaunay: Kommando nicht gefunden.
qdelaunay: kommandot finns inte
qdelaunay: komut yok
qdelaunay: nie znaleziono polecenia
qdelaunay: níor aimsíodh an t-ordú
qdelaunay: no se encontró la orden
qdelaunay: no s'ha trobat l'ordre
qdelaunay: opdracht niet gevonden
qdelaunay: parancs nem található
qdelaunay: perintah tidak ditemukan
qdelaunay: príkaz nenájdený
qdelaunay: příkaz nenalezen
qdelaunay: команда не найдена
qdelaunay: командата не е открита
qdelaunay: 命令找不到
qdelaunay: コマンドが見つかりません