aterm: 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/aterm - from package: aterm

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

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