vdir: 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/vdir - from package: coreutils

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

On Debian possible default full paths are:

/bin/vdir - from package: coreutils

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

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