dvb-fe-tool: 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/dvb-fe-tool - from package: v4l-utils

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

On Debian possible default full paths are:

/usr/bin/dvb-fe-tool - from package: dvb-tools

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

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