ruscreen: 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 Debian possible default full paths are:

/usr/bin/ruscreen - from package: autossh

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

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