slcan_attach: 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/slcan_attach - from package: can-utils

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

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