gs: 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/gs - from package: ghostscript

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

On Debian possible default full paths are:

/usr/bin/gs - from package: ghostscript

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

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