cmp: 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/cmp - from package: diffutils

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

On Debian possible default full paths are:

/usr/bin/cmp - from package: diffutils
/usr/lib/plan9/bin/cmp - from package: 9base

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

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