ksplice-undo: 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/sbin/ksplice-undo - from package: ksplice

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

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