shpadd: 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/shpadd - from package: shapelib

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

On Debian possible default full paths are:

/usr/bin/shpadd - from package: shapelib

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

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