psxy: 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/psxy - 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/psxy - from package: GMT

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

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