ghostview: 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/ghostview - from package: gv

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

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