yelp-check: 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/yelp-check - from package: yelp-tools

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

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