gtkterm: 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/gtkterm - from package: gtkterm

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

On Debian possible default full paths are:

/usr/bin/gtkterm - from package: gtkterm

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

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