atrm: 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/atrm - from package: at

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

On Debian possible default full paths are:

/usr/bin/atrm - from package: at

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

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