dislocker-file: 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/dislocker-file - from package: dislocker

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

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