gserialver: 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/gserialver - from package: libgcj

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

On Debian possible default full paths are:

/usr/bin/gserialver - from package: gcj-jdk

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

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