uniq: 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/uniq - from package: coreutils

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

On Debian possible default full paths are:

/usr/bin/uniq - from package: coreutils
/usr/lib/plan9/bin/uniq - from package: 9base

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

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