jailtest: 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/jailtest - from package: uml_utilities

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

On Debian possible default full paths are:

/usr/bin/jailtest - from package: uml-utilities

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

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