valgrind: 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/valgrind - from package: valgrind

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

On Debian possible default full paths are:

/usr/bin/valgrind - from package: valgrind

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

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