gdk-pixbuf-csource: command not found

Have You tried accessing the binary with the full path?

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/gdk-pixbuf-csource - from package: gdk-pixbuf2-devel

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

On Debian possible default full paths are:

/usr/bin/gdk-pixbuf-csource - from package: libgdk-pixbuf2.0-dev

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