Which part of "System configuration has been modified" ?

[hreftools2014cisco]

This question is about a CISCO1941/K9 router, Version 15.0(1r)M15.

When I type

reload in 4

it asks me

System configuration has been modified. Save? [yes/no]:
% Please answer 'yes' or 'no'.

even though

show archive config differences system:running-config nvram:startup

gives

!Contextual Config Diffs:
!No changes were found

and

show running

gives

Current configuration : 5031 bytes
!
! No configuration change since last restart

My question is: how can I determine WHAT system configuration has been modified?

As far as I know, the only thing changed would be the terminal length which I occasionally toggle for use with session logging with Putty, i.e.

terminal length 0.

I would really appreciate some guidance here. This router has been in production for months and I don't want to break anything (obviously).  I need to make one change to the access-list config and wanted to protect myself by telling it to reload in 4, and then I would most likely reload cancel in about 1 minute.  But now I am worried about this save yes/no question.

Thank you.

[Zach S]

The command you used: "show archive config differences nvram:startup-config system:running-config" is really the best tool for the job. That takes the dumps of each config and does a diff (comparison) between the two for any differences. If you don't trust the diff, you can always copy each config to a text file and do a manual inspection, or on a Linux system use the comm and diff <file1> <file2>.

If you are worried about losing your config, you can send your start up config an FTP, TFTP, SCP, etc.. server if you have one available, via copy start <protocol>://<ip address of FTP server>