activitygen: 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/activitygen - from package: sumo

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