pc_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 Debian possible default full paths are:

/usr/bin/pc_query - from package: pycarddav

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

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