cdfimprovechk: 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/cdfimprovechk - from package: cdftools

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

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