pcl_modeler: 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 Debian possible default full paths are:

/usr/bin/pcl_modeler - from package: pcl-tools

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

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