scalpel: 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 CentOS possible default full paths are:

/usr/bin/scalpel - from package: scalpel

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/scalpel - from package: scalpel

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

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