lsf: 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/share/doc/mh-book/examples/mh/bin/lsf - from package: mh-book

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

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