gifcolor: 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/gifcolor - from package: giflib-utils

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

On Debian possible default full paths are:

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

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

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