pmxchords: 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/pmxchords - from package: texlive-music

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

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