svnshell: 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/bin/svnshell - from package: python-subversion

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