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

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

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