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  Arif 01:44:07 pm on January 25, 2012 | 0 | # |
  Tags: regexp, shell script

  grep omit empty lines:

  cat <something> | grep -v "^$"

  I keep forgetting this regexp of “match expression at the star of the line”: the “^”

   

• Arif 06:39:59 am on January 10, 2012 | 0 | # |
  Tags: device, shell script

  Checking whether /dev/video0 or /dev/ttyUSB0 exists or not (module is installed & probed). They're recognized as "character special file" in bash

  [ -b /dev/ttyUSB0 ] && echo "char special file found" || echo "char special file not found"

  Compare the above to "block special file"

  [ -b /dev/sda ] && echo "block special file found" || echo "block special file not found"

   

• Arif 01:52:10 pm on February 12, 2011 | 0 | # |
  Tags: regexp, shell script, Unix

  Unix time conversion

  $ EPOCH=1297515579843 $ echo $EPOCH | cut -c1-10 1297515579   $ echo $EPOCH | cut -c1-10 | awk '{print strftime("%c",$1)}' Sat 12 Feb 2011 07:59:39 PM WIT

   

• Arif 10:34:14 am on March 17, 2010 | 0 | # |
  Tags: multithreading, shell script

  $ sleep 120 && touch 120 & sleep 4 && touch 4

  So, how are those file touch comes up in sequence (watch the creation time)

  $ ls -l total 160 -rw-r--r-- 1 arif arif 0 2010-03-17 17:28 120 -rw-r--r-- 1 arif arif 0 2010-03-17 17:27 4 ...