preprocess: 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/preprocess - from package: python2-preprocess

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/preprocess - from package: preprocess
/usr/share/doc/pegasus-wms-doc/tutorial/bin/preprocess - from package: pegasus-wms-doc

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

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