fs: 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/fs - from package: openafs-client

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

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