splitdiff: 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/splitdiff - from package: patchutils

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

On Debian possible default full paths are:

/usr/bin/splitdiff - from package: patchutils

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

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