gedit: 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/gedit - from package: gedit

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

On Debian possible default full paths are:

/usr/bin/gedit - from package: gedit

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

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