ctrlaltdel: 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 CentOS possible default full paths are:

/sbin/ctrlaltdel - from package: util-linux-ng

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/sbin/ctrlaltdel - from package: util-linux

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

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