olsr_switch: 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/olsr_switch - from package: olsrd

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

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