freq: 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/lib/plan9/bin/freq - from package: 9base

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

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