readpst: 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/readpst - from package: libpst

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

On Debian possible default full paths are:

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

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

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