syrthes-pp: 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/syrthes-pp - from package: syrthes-tools
/usr/lib/syrthes/bin/syrthes-pp - from package: syrthes-tools

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

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