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Unix

A wee jot about Mosh

I have been using Mosh for quite a number of years now; it is a notionally “mobile” shell that nicely supports devices with intermittent connectivity. On occasion, I have used it as an alternative protocol to ssh when using my laptops/tablets/phones to connect to shell sessions.

Its main merits (to me) are that:

  • Sessions can survive even fairly long connectivity outages. The more I use tmux to manage sessions on servers, the less that matters, but it is still a useful convenience particularly with connections from my phone.
  • Rather than replaying every keystroke (or every receipt of a character of a log file /bin/cat’ed to stdout), it maintains the state of the screen, so it can refresh the screen, skipping over long-irrelevant output, which is an extraordinary network performance improvement if one is browsing server logs…

Curiously, every so often, and this is why I thought to blog about this, I periodically still get forwarded notifications that people continue to report on issue #98 which I helpt report on back in 2012. I was a bit nonplussed this week to notice another update to this that indicates that people are continue to use (or at least reference) my circa-2012 workaround to issues getting Mosh to connect across systems with slightly differing ideas of UTF-8. I suppose I should be proud that my workaround (which is to explicitly pass LANG and LC_ALL values to mosh client and server programs) continues to seem a relevant solution. I have shell scripts lurking around that are almost 8 years old for doing mosh connections in my local environments that use this. I am, however, a wee bit disappointed that nearly 8 years of further development hasn’t made it unnecessary to tweak these environment aspects.

It is a somewhat happy thing that Mosh’s code base is stable enough (and I note it’s included in numerous Linux and BSD distributions, as well as having support in Android apps such as JuiceSSH) that it is, of late, seeing new commits only every few months.

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