xbindkeys_show: 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/xbindkeys_show - from package: xbindkeys

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

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