pidgin: 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/pidgin - from package: pidgin

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

On Debian possible default full paths are:

/usr/bin/pidgin - from package: pidgin-sipe
/usr/bin/pidgin - from package: pidgin

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

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