[libvirt] [PATCH] schematestutils.sh: improve shell portability: avoid "echo -e"

Eric Blake eblake at redhat.com
Wed Apr 14 14:31:34 UTC 2010

On 04/14/2010 05:28 AM, Jim Meyering wrote:
> echo -e is not portable.
> This is the sole remaining use in all of libvirt.


How'd you find it?  I know we've talked about adding a maint.mk check to
help automate some of this (was it over on the bug-grep list?), but I
still haven't thought of a good regexp that doesn't suffer from too many
false positives (in particular, distinguishing between \ as arguments to
echo vs. \ as line continuation can be hard) while still catching the
worst offenders.  Right now, about the best regex I can think of is:

'echo .?[$-]'

which will filter out:

echo -n oops
echo -e oops
echo "$oops"

where the first two are blatantly wrong, and the third might be a false
positive if you can audit $oops for safety.  It would also have a FP on:

echo a-b

although that is less likely, and it totally misses echo 'a\\b', but you
can only do so much.

Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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