grconvert: 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/grconvert - from package: grace

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

On Debian possible default full paths are:

/usr/bin/grconvert - from package: grace

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

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