gmtlegs: 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/gmtlegs - from package: GMT

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

On Debian possible default full paths are:

/usr/lib/gmt/bin/gmtlegs - from package: GMT

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

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