psmeca: 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/psmeca - 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/psmeca - from package: GMT

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

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