ar86: 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/ar86 - from package: dev86

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

On Debian possible default full paths are:

/usr/bin/ar86 - from package: bin86

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

Error in other languages:
ar86: bevel nie gevind nie
ar86: comandă negăsită
ar86: comando não encontrado
ar86: commande introuvable
ar86: command not found
ar86: käsku ei ole
ar86: không tìm thấy lệnh
ar86: komanda nerasta
ar86: Kommando nicht gefunden.
ar86: kommandot finns inte
ar86: komut yok
ar86: nie znaleziono polecenia
ar86: níor aimsíodh an t-ordú
ar86: no se encontró la orden
ar86: no s'ha trobat l'ordre
ar86: opdracht niet gevonden
ar86: parancs nem található
ar86: perintah tidak ditemukan
ar86: príkaz nenájdený
ar86: příkaz nenalezen
ar86: команда не найдена
ar86: командата не е открита
ar86: 命令找不到
ar86: コマンドが見つかりません