So, consider following scenario: virsh # migrate --help In this case migrate help is printed out. So far so good. However, you start writing this long migrate command (I bet you know the arguments there can get quite long), but then, at some point you need to print out the help. Something like this: virsh # migrate --copy-storage-all --migrate-disks --help In this specific case you just want to see the format that --migrate-disks accepts. So you append --help and expect help to be printed out. Well, it will not, because "--help" is taken as data to --migrate-disks. Therefore we will get this error instead: virsh # migrate --copy-storage-all --migrate-disks --help error: command 'migrate' requires <domain> option error: command 'migrate' requires <desturi> option Teach our parsing code, that --help may occur even in argument data, and therefore anywhere on the command line. Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- tools/vsh.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

On 21.10.2015 13:19, Peter Krempa wrote: > On Wed, Oct 21, 2015 at 10:48:13 +0200, Michal Privoznik wrote: >> So, consider following scenario: >> >> virsh # migrate --help >> >> In this case migrate help is printed out. So far so good. >> However, you start writing this long migrate command (I bet you >> know the arguments there can get quite long), but then, at some >> point you need to print out the help. Something like this: >> >> virsh # migrate --copy-storage-all --migrate-disks --help >> >> In this specific case you just want to see the format that >> --migrate-disks accepts. So you append --help and expect help to >> be printed out. Well, it will not, because "--help" is taken as >> data to --migrate-disks. Therefore we will get this error >> instead: >> >> virsh # migrate --copy-storage-all --migrate-disks --help >> error: command 'migrate' requires <domain> option >> error: command 'migrate' requires <desturi> option >> >> Teach our parsing code, that --help may occur even in argument >> data, and therefore anywhere on the command line. >> >> Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; >> --- >> tools/vsh.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> > > The following then won't be possible: > > $ virsh start --domain --help > Domain --help started > > $ virsh list > Id Name State > ---------------------------------------------------- > 2 --help running > > $ virsh destroy --domain --help > Domain --help destroyed > > > If you are curious whether such config is actually valid ... > > # virt-xml-validate /etc/libvirt/qemu/--help.xml > /etc/libvirt/qemu/--help.xml validates > > Since the schema looks like: > <define name="domainName"> > <data type="string"> > <!-- Use literal newline instead of \n for bug in libxml2 2.7.6 --> > <param name="pattern">[^ > ]+</param> > </data> > </define> > > Peter > Well, I'd say <not_personal>if you are that stupid to call your domain like that, you should suffer</not_personal>, but I don't care that much if this patch goes in or not.

> In this case migrate help is printed out. So far so good. > However, you start writing this long migrate command (I bet you > know the arguments there can get quite long), but then, at some > point you need to print out the help. Something like this: > > virsh # migrate --copy-storage-all --migrate-disks --help > > In this specific case you just want to see the format that > --migrate-disks accepts. So you append --help and expect help to > be printed out. Well, it will not, because "--help" is taken as > data to --migrate-disks. But this is the behavior of ALL applications that use getopt_long(): $ ls --block-size --help ls: invalid --block-size argument '--help' NACK; if you use --help in the position where it will be eaten as the argument to an incomplete long option, that's too bad for you, but we shouldn't special case it differently than getopt_long().