pmsleep: 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/libexec/pcp/bin/pmsleep - from package: pcp

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

On Debian possible default full paths are:

/usr/lib/pcp/bin/pmsleep - from package: pcp

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

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