ex3_acceptor: 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/ex3_acceptor - from package: ctn

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

Error in other languages:
ex3_acceptor: bevel nie gevind nie
ex3_acceptor: comandă negăsită
ex3_acceptor: comando não encontrado
ex3_acceptor: commande introuvable
ex3_acceptor: command not found
ex3_acceptor: käsku ei ole
ex3_acceptor: không tìm thấy lệnh
ex3_acceptor: komanda nerasta
ex3_acceptor: Kommando nicht gefunden.
ex3_acceptor: kommandot finns inte
ex3_acceptor: komut yok
ex3_acceptor: nie znaleziono polecenia
ex3_acceptor: níor aimsíodh an t-ordú
ex3_acceptor: no se encontró la orden
ex3_acceptor: no s'ha trobat l'ordre
ex3_acceptor: opdracht niet gevonden
ex3_acceptor: parancs nem található
ex3_acceptor: perintah tidak ditemukan
ex3_acceptor: príkaz nenájdený
ex3_acceptor: příkaz nenalezen
ex3_acceptor: команда не найдена
ex3_acceptor: командата не е открита
ex3_acceptor: 命令找不到
ex3_acceptor: コマンドが見つかりません