sequel: 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/share/gems/bin/sequel - from package: rubygem-sequel
/usr/share/gems/gems/sequel-4.37.0/bin/sequel - from package: rubygem-sequel

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

On Debian possible default full paths are:

/usr/bin/sequel - from package: ruby-sequel

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

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