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37 lines
658 B
Bash
37 lines
658 B
Bash
#! /bin/sh
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# sparsefile - create sparse files conveniently
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#
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# depends on dd and dc commands.
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usage() {
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echo "usage: `basename $0` {10M|10G|10T} {filename}" 1>&2
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}
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size=$1
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if test "$size" = "-h"; then
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usage
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exit
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fi
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fnam=$2
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die() {
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usage
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exit 1
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}
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set -e
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units=`echo "$size" | sed 's!.*\(.\)$!\1!'`
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n=`echo "$size" | sed 's!\(.*\).$!\1!'`
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test "$units" && test "$n" && test "$units" != "$n" || die
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case "$units" in
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M)
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seek=`echo "$n 1024 * 1 - p" | dc` ;;
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G)
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seek=`echo "$n 1024 1024 * * 1 - p" | dc` ;;
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T)
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seek=`echo "$n 1024 1024 1024 * * * 1 - p" | dc` ;;
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*)
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die
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;;
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esac
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sh -xc "dd bs=1k count=1 if=/dev/zero of=$fnam seek=$seek"
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ls -lh "$fnam"
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