apenwarr-redo/t/102-empty/touchtest.do

echo 'echo hello' >touch1.do
redo touch1
[ -e touch1 ] || exit 55
rm -f touch1
echo 'touch $3' >touch1.do
redo touch1
[ -e touch1 ] || exit 66
[ -z "$(cat touch1)" ] || exit 77
rm -f touch1.do
$3 and stdout no longer refer to the same file. This is slightly inelegant, as the old style echo foo echo blah chmod a+x $3 doesn't work anymore; the stuff you wrote to stdout didn't end up in $3. You can rewrite it as: exec >$3 echo foo echo blah chmod a+x $3 Anyway, it's better this way, because now we can tell the difference between a zero-length $3 and a nonexistent one. A .do script can thus produce either one and we'll either delete the target or move the empty $3 to replace it, whichever is right. As a bonus, this simplifies our detection of whether you did something weird with overlapping changes to stdout and $3. 2010-12-11 00:29:04 -08:00			`echo 'echo hello' >touch1.do`
			`redo touch1`
			`[ -e touch1 ] \|\| exit 55`
			`rm -f touch1`
			`echo 'touch $3' >touch1.do`
			`redo touch1`
			`[ -e touch1 ] \|\| exit 66`
			`[ -z "$(cat touch1)" ] \|\| exit 77`
			`rm -f touch1.do`