ssematch: 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/ssematch - from package: embassy-domainatrix

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