dx: 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/dx - from package: dx
/usr/lib64/dx/bin/dx - from package: dx

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

On Debian possible default full paths are:

/usr/bin/dx - from package: dx
/usr/lib/dx/bin/dx - from package: dx

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

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