cf: 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/cf - from package: confluence

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

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