showttf: 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/showttf - from package: fontforge-extras

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

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