gdb-multiarch: 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/gdb-multiarch - from package: gdb-multiarch

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

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