usgs2sdf: 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/usgs2sdf - from package: splat

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

Error in other languages:
usgs2sdf: bevel nie gevind nie
usgs2sdf: comandă negăsită
usgs2sdf: comando não encontrado
usgs2sdf: commande introuvable
usgs2sdf: command not found
usgs2sdf: käsku ei ole
usgs2sdf: không tìm thấy lệnh
usgs2sdf: komanda nerasta
usgs2sdf: Kommando nicht gefunden.
usgs2sdf: kommandot finns inte
usgs2sdf: komut yok
usgs2sdf: nie znaleziono polecenia
usgs2sdf: níor aimsíodh an t-ordú
usgs2sdf: no se encontró la orden
usgs2sdf: no s'ha trobat l'ordre
usgs2sdf: opdracht niet gevonden
usgs2sdf: parancs nem található
usgs2sdf: perintah tidak ditemukan
usgs2sdf: príkaz nenájdený
usgs2sdf: příkaz nenalezen
usgs2sdf: команда не найдена
usgs2sdf: командата не е открита
usgs2sdf: 命令找不到
usgs2sdf: コマンドが見つかりません