mtcp_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/bin/mtcp_restart - from package: dmtcp

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

On Debian possible default full paths are:

/usr/bin/mtcp_restart - from package: dmtcp

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

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