a2j: command not found

Have You tried accessing the binary with the full path?

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/a2j - from package: a2jmidid

You may install the required package with command apt-get install {package}
Error in other languages:
a2j: bevel nie gevind nie
a2j: comandă negăsită
a2j: comando não encontrado
a2j: commande introuvable
a2j: command not found
a2j: käsku ei ole
a2j: không tìm thấy lệnh
a2j: komanda nerasta
a2j: Kommando nicht gefunden.
a2j: kommandot finns inte
a2j: komut yok
a2j: nie znaleziono polecenia
a2j: níor aimsíodh an t-ordú
a2j: no se encontró la orden
a2j: no s'ha trobat l'ordre
a2j: opdracht niet gevonden
a2j: parancs nem található
a2j: perintah tidak ditemukan
a2j: príkaz nenájdený
a2j: příkaz nenalezen
a2j: команда не найдена
a2j: командата не е открита
a2j: 命令找不到
a2j: コマンドが見つかりません