unipng2hex: 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/unipng2hex - from package: unifont-bin

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

Error in other languages:
unipng2hex: bevel nie gevind nie
unipng2hex: comandă negăsită
unipng2hex: comando não encontrado
unipng2hex: commande introuvable
unipng2hex: command not found
unipng2hex: käsku ei ole
unipng2hex: không tìm thấy lệnh
unipng2hex: komanda nerasta
unipng2hex: Kommando nicht gefunden.
unipng2hex: kommandot finns inte
unipng2hex: komut yok
unipng2hex: nie znaleziono polecenia
unipng2hex: níor aimsíodh an t-ordú
unipng2hex: no se encontró la orden
unipng2hex: no s'ha trobat l'ordre
unipng2hex: opdracht niet gevonden
unipng2hex: parancs nem található
unipng2hex: perintah tidak ditemukan
unipng2hex: príkaz nenájdený
unipng2hex: příkaz nenalezen
unipng2hex: команда не найдена
unipng2hex: командата не е открита
unipng2hex: 命令找不到
unipng2hex: コマンドが見つかりません