fwrestart: 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/fwrestart - from package: fwrestart

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

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