tweak: 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/tweak - from package: tweak

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

On Debian possible default full paths are:

/usr/bin/tweak - from package: tweak

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

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