xentrace_setmask: 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/lib/xen-4.4/bin/xentrace_setmask - from package: xen-utils-4.4
/usr/sbin/xentrace_setmask - from package: xen-utils-common

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