pcl_ni_agast: command not found

Have You tried accessing the binary with the full path?

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_ni_agast - from package: pcl-tools

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