tox: 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/tox - from package: python-tox

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

On Debian possible default full paths are:

/usr/bin/tox - from package: python-tox

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

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