| Message ID | 1448530892-4893-1-git-send-email-yamamoto@midokura.com |
|---|---|
| State | Accepted |
| Headers | show |
On Thu, Nov 26, 2015 at 06:41:30PM +0900, YAMAMOTO Takashi wrote: > While (surprisingly to me) bash interprets $10 as ${1}0, > many other shells, including NetBSD's /bin/sh, interpret it as ${10}. The code-changes look fine to me but I wonder if the changelog could be made a bit clearer. Something like: ovn.at: Use {} to make variable expansion less ambiguous While (surprisingly to me) bash interprets $10 as ${1}0, many other shells, including NetBSD's /bin/sh, interpret it as ${10}. Also use already assigned named variables rather than positional parameters to make things a little more readable. > > Signed-off-by: YAMAMOTO Takashi <yamamoto@midokura.com> > --- > tests/ovn.at | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tests/ovn.at b/tests/ovn.at > index 68fcc9a..de0a830 100644 > --- a/tests/ovn.at > +++ b/tests/ovn.at > @@ -964,7 +964,7 @@ done > test_ip() { > # This packet has bad checksums but logical L3 routing doesn't check. > local inport=$1 src_mac=$2 dst_mac=$3 src_ip=$4 dst_ip=$5 > - local packet=$3$208004500001c0000000040110000$4$50035111100080000 > + local packet=${dst_mac}${src_mac}08004500001c0000000040110000${src_ip}${dst_ip}0035111100080000 > shift; shift; shift; shift; shift > hv=hv`vif_to_hv $inport` > as $hv ovs-appctl netdev-dummy/receive vif$inport $packet > -- > 2.4.9 (Apple Git-60) > > _______________________________________________ > dev mailing list > dev@openvswitch.org > http://openvswitch.org/mailman/listinfo/dev
On Thu, Nov 26, 2015 at 06:41:30PM +0900, YAMAMOTO Takashi wrote: > While (surprisingly to me) bash interprets $10 as ${1}0, > many other shells, including NetBSD's /bin/sh, interpret it as ${10}. > > Signed-off-by: YAMAMOTO Takashi <yamamoto@midokura.com> Acked-by: Ben Pfaff <blp@ovn.org> I guess that this is documented in the Autoconf manual, but I had never really paid attention before: '${10}' The 10th, 11th, ... positional parameters can be accessed only after a 'shift'. The 7th Edition shell reported an error if given '${10}', and Solaris 10 '/bin/sh' still acts that way: $ set 1 2 3 4 5 6 7 8 9 10 $ echo ${10} bad substitution Conversely, not all shells obey the Posix rule that when braces are omitted, multiple digits beyond a '$' imply the single-digit positional parameter expansion concatenated with the remaining literal digits. To work around the issue, you must use braces. $ bash -c 'set a b c d e f g h i j; echo $10 ${1}0' a0 a0 $ dash -c 'set a b c d e f g h i j; echo $10 ${1}0' j a0
On Sat, Nov 28, 2015 at 3:17 AM, Ben Pfaff <blp@ovn.org> wrote: > On Thu, Nov 26, 2015 at 06:41:30PM +0900, YAMAMOTO Takashi wrote: >> While (surprisingly to me) bash interprets $10 as ${1}0, >> many other shells, including NetBSD's /bin/sh, interpret it as ${10}. >> >> Signed-off-by: YAMAMOTO Takashi <yamamoto@midokura.com> > > Acked-by: Ben Pfaff <blp@ovn.org> pushed with the commit message updated as Simon suggested. > > I guess that this is documented in the Autoconf manual, but I had never > really paid attention before: thank you. > > '${10}' > The 10th, 11th, ... positional parameters can be accessed only > after a 'shift'. The 7th Edition shell reported an error if given > '${10}', and Solaris 10 '/bin/sh' still acts that way: > > $ set 1 2 3 4 5 6 7 8 9 10 > $ echo ${10} > bad substitution > > Conversely, not all shells obey the Posix rule that when braces are > omitted, multiple digits beyond a '$' imply the single-digit > positional parameter expansion concatenated with the remaining > literal digits. To work around the issue, you must use braces. > > $ bash -c 'set a b c d e f g h i j; echo $10 ${1}0' > a0 a0 > $ dash -c 'set a b c d e f g h i j; echo $10 ${1}0' > j a0
diff --git a/tests/ovn.at b/tests/ovn.at index 68fcc9a..de0a830 100644 --- a/tests/ovn.at +++ b/tests/ovn.at @@ -964,7 +964,7 @@ done test_ip() { # This packet has bad checksums but logical L3 routing doesn't check. local inport=$1 src_mac=$2 dst_mac=$3 src_ip=$4 dst_ip=$5 - local packet=$3$208004500001c0000000040110000$4$50035111100080000 + local packet=${dst_mac}${src_mac}08004500001c0000000040110000${src_ip}${dst_ip}0035111100080000 shift; shift; shift; shift; shift hv=hv`vif_to_hv $inport` as $hv ovs-appctl netdev-dummy/receive vif$inport $packet
While (surprisingly to me) bash interprets $10 as ${1}0, many other shells, including NetBSD's /bin/sh, interpret it as ${10}. Signed-off-by: YAMAMOTO Takashi <yamamoto@midokura.com> --- tests/ovn.at | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)