swfstrings: command not found

Have You tried accessing the binary with the full path?

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/lib/debug/usr/bin/swfstrings - from package: swftools-dbg
/usr/bin/swfstrings - from package: swftools

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