winswitch_ssh_Xnest: 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/winswitch_ssh_Xnest - from package: winswitch

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

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