edofic's comments

edofic · on April 14, 2023

Yes, this is a great example of what I meant with "interactive" client. It takes over the input and output and has it's own shell. Instead I wanted something that looks and feels more like a regular unix tool. Especially that I can put the prompt on the command line (or stdin) and get output on stdout. Because then I can pipe the output and avoid copy-pasting. Small difference but a big quality of life improvement for me.

edofic · on April 15, 2016

Already merged :)

edofic · on Aug 27, 2015

A mandatory smart-ass Haskell response

    import System.Environment (getArgs)
    main = do
      [str] <- getArgs
      putStrLn $ take 12 str

nicolast · on Aug 27, 2015

Now with more operators!

    import System.Environment (getArgs)
    main = putStrLn =<< take 12 . head <$> getArgs

;-)

joeyh · on Aug 27, 2015

The actual smart-ass haskell response is simply "take 12". The spec didn't specify this needed to be a impure shell command, so a pure function is obviously better.

coldtea · on Aug 27, 2015

Well, for smart-ass (and I know you meant it as a joke) is not very impressive. Don't do anything more than the others, and the syntax is not so great either.

Veedrac · on Aug 27, 2015

On the contrary, his is the only one that crashes when more arguments than expected are passed. Hooray progress!

edofic · on May 6, 2015

http://webcache.googleusercontent.com/search?q=cache:http://...

google cache, text only view

edofic · on Jan 27, 2015

"Since there's no way to roll back server upgrades"

It is if you run a modern filesystem like ZFS or btrfs. You just do a cheap snapshot before upgrading(can be automated) and roll back if there are problems. Even works with lvm.

KaiserPro · on Jan 28, 2015

Sadly as zfs isn't as widely available as I'd like, you can use LVM to provide snapshots.

Its not as friendly as ZFS snapshots, but it is at least available in centos 5 https://www.centos.org/docs/5/html/Cluster_Logical_Volume_Ma...

(sadly somethings need long term support)

lsc · on Jan 28, 2015

rolling back a LVM snapshot involves dding off the snapshot, and on to whatever you want your production disk to be (or just running off the snapshot forever, which has.... performance consequences with LVM.)

Yes, LVM snapshots exist, but they are of limited utility compared to ZFS and the like.

I've been experimenting with CentOS6 and ZFS on Linux; so far it looks pretty good. it handles failing consumer grade hard drives vastly better than lvm on md, and snapshots are inexpensive.

b101010 · on Jan 28, 2015

You can also roll back lvm snapshots using the merge option

https://access.redhat.com/documentation/en-US/Red_Hat_Enterp...

lsc · on Jan 28, 2015

nice. I had not seen that before... that makes it a lot more useful.

KaiserPro · on Jan 28, 2015

Oh yes, LVM is abhorrent, along with mdadm.

Thats why I'm not so happy about the direction the tools are going with BTRFS. If ZFS isn't around, LVM is your only real option.

However, RHEL usually sets up LVM, so you might as well use it.

thaumaturgy · on Jan 27, 2015

Ooh, thanks. That's a good idea. I'd never considered running ZFS on my small servers.

keithpeter · on Jan 27, 2015

Or perhaps simply gzip of the / partition before upgrading. If insuperable problems, zap new / and restore old known working one?

Assuming data/sites are on different partitions.

kbenson · on Jan 28, 2015

While initially conceptually easier to grasp, that is far inferior to using a snapshot.

Here's a short list of ways in which that may cause you problems:

1) gzip of a path is not point in time, synced files may no longer be in sync since they were backed up at slightly different times (e.g. I hope you didn't expect database consistency to actually mean anything).

2) gzip of a path will take a while, because it has to actually function on every file (a snapshot is generally copy on write, meaning it's "free" (not quite) for every file until it's changed. Throw away the snapshot before a change and there's no need to copy the file.

3) gzip will take more room (see #2)

keithpeter · on Jan 28, 2015

Excellent reply. The implications of a significant number of transactions per minute had escaped me.

davexunit · on Jan 28, 2015

Or, you could try out NixOS/GuixSD, which support transactional upgrades and rollbacks for the full system. No need to take a disk image (outside of your normal backup routine, of course).

vacri · on Jan 28, 2015

btrfs still isn't production ready. I went to a talk from a btrfs dev two weeks ago, and it was still "use btrfs with caveats", not "just use btrfs".

vel0city · on Jan 28, 2015

Or, if you're using VMs, just take a snapshot and roll back if something doesn't work right. For anything that isn't virtualized, there's ZFS.

edofic · on June 10, 2014

Slides from Marlow from 9 months ago about Haxl and it's workings https://github.com/meiersi/HaskellerZ/blob/master/meetups/20...

edofic · on Feb 24, 2014

try hdevtools plugin for your editor.

edofic · on Sept 27, 2013

I made a few android apps with scala. What's not working for you?

edofic · on Feb 6, 2013

new json api is bloody awesome! and when you add reactive mongo in the mix... oh my god

edofic · on Jan 27, 2013

oh boy...religious wars are a coming