echo foo | m4 -Dfoo=\`bar\' -Dbar=baz
On Mon, Oct 12, 2020 at 8:24 AM Eric Blake <ebl...@redhat.com> wrote: > On 10/12/20 5:27 AM, Wolf wrote: > > Hello, > > > > Not subscribed to the list, so please CC. > > That's standard practice anyway ;) > > > > > I have m4 template that contains macro, that I do not know the value of > > (provided by user). That can lead to user setting the macro to name of > > another macro, like: > > > > $ echo foo | m4 -Dfoo=bar -Dbar=baz > > baz > > > > Now, I understand why it happens and that it is expected. However, due > > to reason stated above, I need the macro to expand just once, so that > > the snippet above would produce `bar`. Is there a way to do so? > > In general, if the user is providing you text rather than something that > should expand as a macro that needs further recursive interpretation, > you should use defn() to get at that text: > > $ echo 'changequote([,])defn([foo])' | m4 -Dfoo=bar -Dbar=baz > bar > > But keep in mind that defn does NOT perform any interpolation of $, > which may introduce its own oddities if the user supplied a macro > definition containing $ that you aren't expanding as a macro. > > -- > Eric Blake, Principal Software Engineer > Red Hat, Inc. +1-919-301-3226 > Virtualization: qemu.org | libvirt.org > > >
