roots: 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/roots - from package: root

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

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