standalone.pyc: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/lib/python2.6/site-packages/viewvc/bin/standalone.pyc - from package: viewvc

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