gnome-character-map: 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/gnome-character-map - from package: gucharmap

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

On Debian possible default full paths are:

/usr/bin/gnome-character-map - from package: gucharmap

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

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