simplesnap: 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/sbin/simplesnap - from package: simplesnap

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