sane-find-scanner: 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/sane-find-scanner - from package: sane-backends

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

On Debian possible default full paths are:

/usr/bin/sane-find-scanner - from package: sane-utils

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

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