tftp: 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/tftp - from package: tftp

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

On Debian possible default full paths are:

/usr/bin/tftp - from package: tftp-hpa
/usr/bin/tftp - from package: tftp

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

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