gifhisto: 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/gifhisto - from package: giflib-utils

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

On Debian possible default full paths are:

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

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

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