xx-svn-review: 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 Debian possible default full paths are:

/usr/bin/xx-svn-review - from package: xxdiff-scripts

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

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