docbook2x-texi: 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/docbook2x-texi - from package: docbook2X

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

Error in other languages:
docbook2x-texi: bevel nie gevind nie
docbook2x-texi: comandă negăsită
docbook2x-texi: comando não encontrado
docbook2x-texi: commande introuvable
docbook2x-texi: command not found
docbook2x-texi: käsku ei ole
docbook2x-texi: không tìm thấy lệnh
docbook2x-texi: komanda nerasta
docbook2x-texi: Kommando nicht gefunden.
docbook2x-texi: kommandot finns inte
docbook2x-texi: komut yok
docbook2x-texi: nie znaleziono polecenia
docbook2x-texi: níor aimsíodh an t-ordú
docbook2x-texi: no se encontró la orden
docbook2x-texi: no s'ha trobat l'ordre
docbook2x-texi: opdracht niet gevonden
docbook2x-texi: parancs nem található
docbook2x-texi: perintah tidak ditemukan
docbook2x-texi: príkaz nenájdený
docbook2x-texi: příkaz nenalezen
docbook2x-texi: команда не найдена
docbook2x-texi: командата не е открита
docbook2x-texi: 命令找不到
docbook2x-texi: コマンドが見つかりません