graphchk: 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/graphchk - from package: metis

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

On Debian possible default full paths are:

/usr/bin/graphchk - from package: metis

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

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