GMT: 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/GMT - from package: GMT

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

On Debian possible default full paths are:

/usr/bin/GMT - from package: GMT
/usr/bin/GMT - from package: libgenome-perl

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

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