pflags: 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 CentOS possible default full paths are:

/usr/bin/pflags - from package: python-linux-procfs

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