uncolor: 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 Debian possible default full paths are:

/usr/bin/uncolor - from package: libterm-extendedcolor-perl

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

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