aesession: 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/aesession - from package: aewm

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

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