nick2ldif: 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 Debian possible default full paths are:

/usr/bin/nick2ldif - from package: pst-utils

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

Error in other languages:
nick2ldif: bevel nie gevind nie
nick2ldif: comandă negăsită
nick2ldif: comando não encontrado
nick2ldif: commande introuvable
nick2ldif: command not found
nick2ldif: käsku ei ole
nick2ldif: không tìm thấy lệnh
nick2ldif: komanda nerasta
nick2ldif: Kommando nicht gefunden.
nick2ldif: kommandot finns inte
nick2ldif: komut yok
nick2ldif: nie znaleziono polecenia
nick2ldif: níor aimsíodh an t-ordú
nick2ldif: no se encontró la orden
nick2ldif: no s'ha trobat l'ordre
nick2ldif: opdracht niet gevonden
nick2ldif: parancs nem található
nick2ldif: perintah tidak ditemukan
nick2ldif: príkaz nenájdený
nick2ldif: příkaz nenalezen
nick2ldif: команда не найдена
nick2ldif: командата не е открита
nick2ldif: 命令找不到
nick2ldif: コマンドが見つかりません