Links: 4 Sep

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:

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:

Sunlight in Europe and the USA in hours per year.