activemq-admin: 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 Debian possible default full paths are:

/usr/bin/activemq-admin - from package: activemq

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

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