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hgbook / en / examples / hook.ws

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cp $EXAMPLE_DIR/data/check_whitespace.py .

hg init a
cd a
echo '[hooks]' > .hg/hgrc
echo "pretxncommit.whitespace = hg export tip | (! grep -qP '^\\+.*[ \\t]$')" >> .hg/hgrc

#$ name: simple

cat .hg/hgrc
echo 'a ' > a
hg commit -A -m 'test with trailing whitespace'