ck-log-system-restart: 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:

/usr/sbin/ck-log-system-restart - from package: ConsoleKit

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

On Debian possible default full paths are:

/usr/sbin/ck-log-system-restart - from package: ConsoleKit

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

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