$ hg init $ touch a $ unset HGUSER $ echo "[ui]" >> .hg/hgrc $ echo "username= foo" >> .hg/hgrc $ echo " bar1" >> .hg/hgrc $ hg ci -Am m adding a abort: username 'foo\nbar1' contains a newline [255] $ rm .hg/hgrc $ HGUSER=`(echo foo; echo bar2)` hg ci -Am m abort: username 'foo\nbar2' contains a newline [255] $ hg ci -Am m -u "`(echo foo; echo bar3)`" transaction abort! rollback completed abort: username 'foo\nbar3' contains a newline! [255]