subsurface: 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/subsurface - from package: subsurface

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

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