#!/bin/sh
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candidate="$1"
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tar=`which $candidate`
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if [ ! -x "$tar" ]; then
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tar=`which tar`
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if [ ! -x "$tar" ]; then
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# echo nothing: no suitable tar found
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exit 1
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fi
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fi
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# Output of 'tar --version' examples:
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# tar (GNU tar) 1.15.1
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# tar (GNU tar) 1.25
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# bsdtar 2.8.3 - libarchive 2.8.3
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version=`$tar --version | head -n 1 | sed 's/^.*\s\([0-9]\+\.\S\+\).*$/\1/'`
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major=`echo "$version" | cut -d. -f1`
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minor=`echo "$version" | cut -d. -f2`
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bugfix=`echo "$version" | cut -d. -f3`
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version_bsd=`$tar --version | grep 'bsdtar'`
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if [ ! -z "${version_bsd}" ] ; then
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# mark as invalid version - not all command line options are available
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major=0
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minor=0
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fi
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# Minimal version = 1.17 (previous versions do not correctly unpack archives
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# containing hard-links if the --strip-components option is used).
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major_min=1
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minor_min=17
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# Maximal version = 1.29 (1.30 changed --numeric-owner output for
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# filenames > 100 characters). This is really a fix for a bug in
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# earlier tar versions regarding deterministic output so it is
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# unlikely to be reverted in later versions.
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major_max=1
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minor_max=29
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if [ $major -lt $major_min -o $major -gt $major_max ]; then
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# echo nothing: no suitable tar found
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exit 1
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fi
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if [ $major -eq $major_min -a $minor -lt $minor_min ]; then
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# echo nothing: no suitable tar found
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exit 1
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fi
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if [ $major -eq $major_max -a $minor -gt $minor_max ]; then
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# echo nothing: no suitable tar found
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exit 1
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fi
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# valid
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echo $tar
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