gnatcheck: 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/gnatcheck - from package: asis-programs

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

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