lsh-writekey: 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/lsh-writekey - from package: lsh-utils

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

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