set_unicharset_properties: 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/set_unicharset_properties - from package: tesseract-ocr

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

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