arduino: 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/arduino - from package: arduino

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

On Debian possible default full paths are:

/usr/bin/arduino - from package: arduino

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

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