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  1. Prepare
  2. Linux Shell
  3. Text Processing
  4. Middle of a Text File
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Middle of a Text File

  • senooken
     + 1 comment

    Sorry for late.

    head -n 22 | tail -n 11 is faster than sed because of multi thread by pipe processing. But head-tail is longer code and spending more CPU resource. (head -num and tail -num are deoprecated option in POSIX.)

    :
## \file      time-middle-of-text.sh

yes | head -n 30 >tmp

echo "sed -n '12,22p' tmp >/dev/null"
time -p sh <<-'EOT'
for i in $(yes | head -n 1000); do
	sed -n '12,22p' tmp >/dev/null
done
EOT

echo "head -n 22 tmp | tail -n 11 >/dev/null"
time -p sh <<-'EOT'
for i in $(yes | head -n 1000); do
	head -n 22 tmp | tail -n 11 >/dev/null
done
EOT

rm -f tmp

    Result:

    sed -n '12,22p' tmp >/dev/null
real 1.14
user 0.02
sys 0.07
head -n 22 tmp | tail -n 11 >/dev/null
real 1.02
user 0.01
sys 0.12