letterize: 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/letterize - from package: letterize

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

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