skip-seek2

实战Linux编程的原代码,希望对学驱动的人能有所帮助

#!/bin/sh
# show how to skip an amount that is smaller than the nominal block size.
# There's a more realistic example in the documentation.

if test "$VERBOSE" = yes; then
  set -x
  dd --version
fi

pwd=`pwd`
tmp=skip-seek.$$
trap 'status=$?; cd $pwd; rm -rf $tmp && exit $status' 0
trap '(exit $?); exit' 1 2 13 15

framework_failure=0
mkdir $tmp || framework_failure=1
cd $tmp || framework_failure=1

if test $framework_failure = 1; then
  echo 'failure in testing framework'
  (exit 1); exit
fi

fail=0

echo LA:3456789abcdef > in || fail=1
(dd bs=1 skip=3 count=0 && dd bs=5) < in > out 2> /dev/null || fail=1
case `cat out` in
  3456789abcdef) ;;
  *) fail=1 ;;
esac

echo LA:3456789abcdef > in || fail=1
(dd bs=1 skip=3 count=0 && dd bs=5 count=2) < in > out 2> /dev/null || fail=1
case `cat out` in
  3456789abc) ;;
  *) fail=1 ;;
esac

(exit $fail); exit