viewvc-loginfo-handler: 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 Debian possible default full paths are:

/usr/sbin/viewvc-loginfo-handler - from package: viewvc-query

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