userinfo: 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/userinfo - from package: usermode-gtk

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

On Debian possible default full paths are:

/usr/bin/userinfo - from package: usermode

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

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