pbc_merge: 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/pbc_merge - from package: parrot-devel

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

On Debian possible default full paths are:

/usr/bin/pbc_merge - from package: parrot-devel

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

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