finger: 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/finger - from package: finger

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

On Debian possible default full paths are:

/usr/bin/finger - from package: finger

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

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