giffix: 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/giffix - from package: giflib-utils

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

On Debian possible default full paths are:

/usr/bin/giffix - from package: giflib-tools

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

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