xsltproc: 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/bin/xsltproc - from package: libxslt

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

On Debian possible default full paths are:

/usr/bin/xsltproc - from package: xsltproc

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

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