unicharset_extractor: 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/unicharset_extractor - from package: tesseract-ocr

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

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