tessa-mpi: 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/tessa-mpi - from package: tessa-mpi

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

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