assimp: 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/assimp - from package: assimp

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

On Debian possible default full paths are:

/usr/bin/assimp - from package: assimp-utils

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

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