gambc-doc: 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/lib64/gambit-c/bin/gambc-doc - from package: gambit-c

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

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