py3status: 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/py3status - from package: py3status

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

Error in other languages:
py3status: bevel nie gevind nie
py3status: comandă negăsită
py3status: comando não encontrado
py3status: commande introuvable
py3status: command not found
py3status: käsku ei ole
py3status: không tìm thấy lệnh
py3status: komanda nerasta
py3status: Kommando nicht gefunden.
py3status: kommandot finns inte
py3status: komut yok
py3status: nie znaleziono polecenia
py3status: níor aimsíodh an t-ordú
py3status: no se encontró la orden
py3status: no s'ha trobat l'ordre
py3status: opdracht niet gevonden
py3status: parancs nem található
py3status: perintah tidak ditemukan
py3status: príkaz nenájdený
py3status: příkaz nenalezen
py3status: команда не найдена
py3status: командата не е открита
py3status: 命令找不到
py3status: コマンドが見つかりません