lhapdf-query: 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/lhapdf-query - from package: python-lhapdf

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

On Debian possible default full paths are:

/usr/bin/lhapdf-query - from package: python-lhapdf

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

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