pssegy: 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/pssegy - 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/pssegy - from package: GMT

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

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