I want to maximize my sd card lifespan and Im wondering if redirecting output to /dev/null will reduce my sd card life.

2 Answers 2


Sending output to /dev/null means "throw it away". It has no impact on your SD card at all. Of course, the commands that you're running prior and piping to /dev/null may well be affecting your SD card.


Anything you redirect to /dev/null gets dumped out an airlock. For example if you were to cat /boot/kernel.img > /dev/null what's happened is effectively nothing. Of course, cat /boot/kernel.img would normally just write to the terminal, which is also only a short-term memory cache on the screen. That never gets written to the SD either. There are generally only very specific instances you might want to write to /dev/null for actual benefit. For example, doing first pass video encoding still prodcues an output file. This you can send to /dev/null to save writes on the card. When you do the second pass of the encoding then you do the actual writing.

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    effectively nothing? cat will still read! Depending on the source that may effectively touch the network and flush several levels of cache and buffers. Mar 24, 2014 at 12:50
  • Ack! Yes, that's right. I meant that in terms of factors affecting SD card life. There may be some tiny, minor wear due to the read, but my point was that in general cat here isn't a command that would be reasonably expected to affect SD card life.
    – Fred
    Mar 24, 2014 at 14:11

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