pdf2ps: 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/pdf2ps - from package: ghostscript

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

On Debian possible default full paths are:

/usr/bin/pdf2ps - from package: ghostscript

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

Error in other languages:
pdf2ps: bevel nie gevind nie
pdf2ps: comandă negăsită
pdf2ps: comando não encontrado
pdf2ps: commande introuvable
pdf2ps: command not found
pdf2ps: käsku ei ole
pdf2ps: không tìm thấy lệnh
pdf2ps: komanda nerasta
pdf2ps: Kommando nicht gefunden.
pdf2ps: kommandot finns inte
pdf2ps: komut yok
pdf2ps: nie znaleziono polecenia
pdf2ps: níor aimsíodh an t-ordú
pdf2ps: no se encontró la orden
pdf2ps: no s'ha trobat l'ordre
pdf2ps: opdracht niet gevonden
pdf2ps: parancs nem található
pdf2ps: perintah tidak ditemukan
pdf2ps: príkaz nenájdený
pdf2ps: příkaz nenalezen
pdf2ps: команда не найдена
pdf2ps: командата не е открита
pdf2ps: 命令找不到
pdf2ps: コマンドが見つかりません