pswiggle: 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/pswiggle - 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/pswiggle - from package: GMT

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

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