September 4, 2013

Links: 4th Sep

§ links     # apple grep iphone kids less osx photos recording rpmdb SA scale signals sunlight yac

This week: technology links and a chart with sunlight hours.


  • grep tricks: grep files recursively, show only filenames where matching string was/wasn’t found.
  • Did you know that:
    • $ less <directory> — shows directory listing
    • $ less <> — shows archive content
  • Teacher’s rumblings “Kids can’t use computers“. Agree to a T.
  • Going back to iPhone [from Android]. Again having pretty much the same thoughts.
  • Reddit: Lessons Learned From Mistakes Made Scaling To 1 Billion Pageviews A Month
  • Start a Web Search in a GUI Browser from the Command Line on Mac OS X
  • Screen recording to an animated GIF on Mac OS X
  • How to know from a child process that its parent exited:
    • a pipe between parent and a child, child gets SIGPIPE when parent exits
    • if a child has not detached, PPID becomes 1 when parent exits
    • Linux-specific: a child can ask kernel to deliver a signal when parent dies by specifying option PR_SET_PDEATHSIG in prctl() syscall
  • Two talks from YAC which I liked:
  • rpmdb locking issues, notorious on RHEL4/5, manifest as a hanging rpm command. To see active locks:
    # cd /var/lib/rpm; /usr/lib/rpm/rpmdb_stat -CA

    Normally there should be no locks, given no rpm command is running. In case there are stale locks, just remove __db.00* files.


  • Learning second language later in life brings brain change
  • Evolution: educating pupils (in Russian)
  • Wonderful photos by National Geographic

Sunlight in Europe and the USA in hours per year

— `If you knew Time as well as I do,' said the Hatter, `you wouldn't talk about wasting IT. It's HIM.'
$ Last updated: Feb 7, 2021 at 13:38 (EET) $