x3270: 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/x3270 - from package: x3270-x11

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

Error in other languages:
x3270: bevel nie gevind nie
x3270: comandă negăsită
x3270: comando não encontrado
x3270: commande introuvable
x3270: command not found
x3270: käsku ei ole
x3270: không tìm thấy lệnh
x3270: komanda nerasta
x3270: Kommando nicht gefunden.
x3270: kommandot finns inte
x3270: komut yok
x3270: nie znaleziono polecenia
x3270: níor aimsíodh an t-ordú
x3270: no se encontró la orden
x3270: no s'ha trobat l'ordre
x3270: opdracht niet gevonden
x3270: parancs nem található
x3270: perintah tidak ditemukan
x3270: príkaz nenájdený
x3270: příkaz nenalezen
x3270: команда не найдена
x3270: командата не е открита
x3270: 命令找不到
x3270: コマンドが見つかりません