dssi_osc_send: 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/dssi_osc_send - from package: dssi-utils

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

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