fort77: 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/fort77 - from package: fort77

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

Error in other languages:
fort77: bevel nie gevind nie
fort77: comandă negăsită
fort77: comando não encontrado
fort77: commande introuvable
fort77: command not found
fort77: käsku ei ole
fort77: không tìm thấy lệnh
fort77: komanda nerasta
fort77: Kommando nicht gefunden.
fort77: kommandot finns inte
fort77: komut yok
fort77: nie znaleziono polecenia
fort77: níor aimsíodh an t-ordú
fort77: no se encontró la orden
fort77: no s'ha trobat l'ordre
fort77: opdracht niet gevonden
fort77: parancs nem található
fort77: perintah tidak ditemukan
fort77: príkaz nenájdený
fort77: příkaz nenalezen
fort77: команда не найдена
fort77: командата не е открита
fort77: 命令找不到
fort77: コマンドが見つかりません