atst-int64: command not found

Have You tried accessing the binary with the full path?

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/lib/debug/usr/bin/atst-int64 - from package: scotch-dbg
/usr/bin/atst-int64 - from package: scotch

You may install the required package with command apt-get install {package}
Error in other languages:
atst-int64: bevel nie gevind nie
atst-int64: comandă negăsită
atst-int64: comando não encontrado
atst-int64: commande introuvable
atst-int64: command not found
atst-int64: käsku ei ole
atst-int64: không tìm thấy lệnh
atst-int64: komanda nerasta
atst-int64: Kommando nicht gefunden.
atst-int64: kommandot finns inte
atst-int64: komut yok
atst-int64: nie znaleziono polecenia
atst-int64: níor aimsíodh an t-ordú
atst-int64: no se encontró la orden
atst-int64: no s'ha trobat l'ordre
atst-int64: opdracht niet gevonden
atst-int64: parancs nem található
atst-int64: perintah tidak ditemukan
atst-int64: príkaz nenájdený
atst-int64: příkaz nenalezen
atst-int64: команда не найдена
atst-int64: командата не е открита
atst-int64: 命令找不到
atst-int64: コマンドが見つかりません