sylseg-sk-training: 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

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/sylseg-sk-training - from package: sylseg-sk

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