gsmartcontrol: 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/gsmartcontrol - from package: gsmartcontrol
/usr/sbin/gsmartcontrol - from package: gsmartcontrol

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

On Debian possible default full paths are:

/usr/bin/gsmartcontrol - from package: gsmartcontrol

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

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