pari: command not found

Have You tried accessing the binary with the full path?

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:

/var/lib/wims/public_html/bin/pari - from package: wims

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