OfflinePlayer: 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/bin/OfflinePlayer - from package: clam-networkeditor

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