weechat-curses: 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/weechat-curses - from package: weechat

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

On Debian possible default full paths are:

/usr/bin/weechat-curses - from package: weechat-curses

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

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