ps4pdf: 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/ps4pdf - from package: texlive-utils

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

On Debian possible default full paths are:

/usr/bin/ps4pdf - from package: texlive-latex-extra

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

Error in other languages:
ps4pdf: bevel nie gevind nie
ps4pdf: comandă negăsită
ps4pdf: comando não encontrado
ps4pdf: commande introuvable
ps4pdf: command not found
ps4pdf: käsku ei ole
ps4pdf: không tìm thấy lệnh
ps4pdf: komanda nerasta
ps4pdf: Kommando nicht gefunden.
ps4pdf: kommandot finns inte
ps4pdf: komut yok
ps4pdf: nie znaleziono polecenia
ps4pdf: níor aimsíodh an t-ordú
ps4pdf: no se encontró la orden
ps4pdf: no s'ha trobat l'ordre
ps4pdf: opdracht niet gevonden
ps4pdf: parancs nem található
ps4pdf: perintah tidak ditemukan
ps4pdf: príkaz nenájdený
ps4pdf: příkaz nenalezen
ps4pdf: команда не найдена
ps4pdf: командата не е открита
ps4pdf: 命令找不到
ps4pdf: コマンドが見つかりません