smem: 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/smem - from package: smem

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

On Debian possible default full paths are:

/usr/bin/smem - from package: smem

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

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