mapproject: 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/mapproject - 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/mapproject - from package: GMT

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

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