svndbadmin: 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/svndbadmin - from package: viewvc

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

On Debian possible default full paths are:

/usr/share/gforge/www/scm/viewvc/bin/svndbadmin - from package: gforge-web-apache2
/usr/lib/viewvc/bin/svndbadmin - from package: viewvc-query

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

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