Technology:

• 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 <archive.zip> — 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:
  • Small service administration
  • Fault-tolerance and load balancing

rpmdb locking issues, notorious on RHEL4/5, manifest as 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.

Other:

• 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.