xsec-c14n: 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/xsec-c14n - from package: xml-security-c-utils

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

Error in other languages:
xsec-c14n: bevel nie gevind nie
xsec-c14n: comandă negăsită
xsec-c14n: comando não encontrado
xsec-c14n: commande introuvable
xsec-c14n: command not found
xsec-c14n: käsku ei ole
xsec-c14n: không tìm thấy lệnh
xsec-c14n: komanda nerasta
xsec-c14n: Kommando nicht gefunden.
xsec-c14n: kommandot finns inte
xsec-c14n: komut yok
xsec-c14n: nie znaleziono polecenia
xsec-c14n: níor aimsíodh an t-ordú
xsec-c14n: no se encontró la orden
xsec-c14n: no s'ha trobat l'ordre
xsec-c14n: opdracht niet gevonden
xsec-c14n: parancs nem található
xsec-c14n: perintah tidak ditemukan
xsec-c14n: príkaz nenájdený
xsec-c14n: příkaz nenalezen
xsec-c14n: команда не найдена
xsec-c14n: командата не е открита
xsec-c14n: 命令找不到
xsec-c14n: コマンドが見つかりません