lssubsys: 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 CentOS possible default full paths are:

/bin/lssubsys - from package: libcgroup

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/lssubsys - from package: cgroup-tools

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

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