set date +90 days in bash script

Question

I have a bash script to get days from AD since password was created. I need it to tell me the expiration date, which is last set date + 90 days

#!/bin/bash

pass="$(ldapsearch -Y GSSAPI -Q -H ldap:///dc%3Dant%2Cdc%3Dwork%2Cdc%3Dcom -b DC=ant,DC=work,DC=com -s sub cn=$1 | grep -Ew 'pwdLastSet:' | awk '{print $2}')"
epoch="$(((${pass}/10000000)-11644473600))"
pwdSet="$(date -d @${epoch})"
expires="$("${pwdSet}" --date +90+days)"

echo "pwdLastSet: "$pwdSet
echo "pwdExpires: "$expires

The line; expires="$("${pwdSet}" --date +90+days)"

Is the problematic one

Answer 1

The line doesn't make any sense. Bash doesn't have anything like date objects in PowerShell; $pwdSet is just a string, and is being interpreted as a command to run.

So you need to use a tool which would take a date and an offset; date -d could be convinced to do this, but it depends on the date format.

However, it's much simpler to adjust the epoch time by adding the needed amount of seconds, and only convert the final result to a date:

expires=$(date -d "@$((epoch + 86400*90))")

1 day is almost always 86400 seconds.