jack_lsp: 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/jack_lsp - from package: jack-audio-connection-kit-example-clients

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

On Debian possible default full paths are:

/usr/bin/jack_lsp - from package: jackd1
/usr/bin/jack_lsp - from package: jackd2

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

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