acfax: 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
/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/acfax - from package: acfax

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