What's the story behind 'nvram commit'? Has it changed?

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jimj
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Joined: 18 Oct 2015
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Location: Sioux Falls SD
PostPosted: Sat Jul 24, 2021 0:22    Post subject: What's the story behind 'nvram commit'? Has it changed? Reply with quote
On the Hardware - DD-WRT Wiki page the nvram commands are explained, including:
Code:
nvram set <variable_name>="<value>"
Change variable value in RAM only
Now you can play with the new settings or test user scripts but this new value will be lost after reboot unless you do nvram commit
and
Code:
nvram commit
Save all changed variables to NVRAM

So based on these two descriptions you MUST run 'nvram commit' after running 'nvram set' if you want your settings to survive a reboot. However, I've never needed to run 'nvram commit'. Anything I configure via 'nvram set' is always saved and always survives a reboot. How could this be?
  1. Do some 'nvram set' variables get saved automatically and not others?
  2. Is there a cron job that frequently runs 'nvram commit' for you?
  3. Did 'nvram commit' used to be needed, but it's no longer needed and the wiki is simply outdated?
  4. Is the behavior I'm seeing is a platform specific quirk? I've only played with command line (CLI) configuration on a Netgear R7800 router starting with build r44719 (currently using r47086).

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blkt
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PostPosted: Sat Jul 24, 2021 1:05    Post subject: Reply with quote
"on reboot (or any other action) the nvram is saved to mtd from RAM"
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kernel-panic69
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PostPosted: Sat Jul 24, 2021 1:21    Post subject: Reply with quote
Nothing like a carryover from your other thread. I'm feeling nice at the moment, and apparently that wiki needs some editing...
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jimj
DD-WRT Novice


Joined: 18 Oct 2015
Posts: 35
Location: Sioux Falls SD
PostPosted: Sat Jul 24, 2021 1:30    Post subject: Reply with quote
blkt wrote:
"on reboot (or any other action) the nvram is saved to mtd from RAM"

Thanks blkt, I think I finally understand. If I run 'nvram set' and want to back out the change I could simply pull the power cord to roll back (as long as I haven't done anything else that would save the config). Likewise if you want to ensure your 'nvram set' commands are saved you should run 'nvram commit' (although clicking "Apply Settings" or rebooting should work too).

kernel-panic69 wrote:
Nothing like a carryover from your other thread. I'm feeling nice at the moment, and apparently that wiki needs some editing...

Thanks kernel-panic69. Lots of great info in Hardware - DD-WRT Wiki, but the saving bit did confuse me. It all makes sense now though.
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