pamchannel: 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/pamchannel - from package: netpbm-progs

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

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