xssstate: 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/xssstate - from package: suckless-tools

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

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