fusioninventory-agent: 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/fusioninventory-agent - from package: fusioninventory-agent

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

On Debian possible default full paths are:

/usr/bin/fusioninventory-agent - from package: fusioninventory-agent

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

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