Orthanc: 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/sbin/Orthanc - from package: orthanc

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