opalc++: 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/opalc++ - from package: libopenmpi-dev

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

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