rsvg-convert: 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/rsvg-convert - from package: librsvg2

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

On Debian possible default full paths are:

/usr/bin/rsvg-convert - from package: librsvg2-bin

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

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