pmsnap: 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/libexec/pcp/bin/pmsnap - from package: pcp-gui

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

On Debian possible default full paths are:

/usr/lib/pcp/bin/pmsnap - from package: pcp-gui

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

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