nsinit: 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:

/usr/bin/nsinit - from package: golang-github-docker-libcontainer

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

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