nm-tool: 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/nm-tool - from package: NetworkManager

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

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