This is the mail archive of the cygwin-apps mailing list for the Cygwin project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH setup 0/3] Setup replacement for incver_ifdep


On 1/28/2016 3:06 PM, Eric Blake wrote:
> On 01/28/2016 11:42 AM, Ken Brown wrote:
>> On 1/28/2016 12:33 PM, Jon Turney wrote:
>>> Future work: I can't see any reason why this script now needs an
>>> independent existence, so it could be absorbed by the info package.
>>
>> That's fine with me.  There will be a new version of texinfo soon (it's
>> currently in pretest), so we can make the transition then.  But I need
>> to understand the script before I take it over, and I'm confused by the
>> command
>>
>>    install-info $f /usr/share/info/dir ||
>>    install-info --entry="* $$f ($f): $$f" $$f /usr/share/info/dir
>>
>> First, what do those double dollar signs mean?
> 
> If this is from a Makefile snippet, it says that $f is a make variable,
> while $$ turns into a literal $f for the shell that make invokes
> (something like:
> 
> install-info foo /usr/share/info/dir || \
>    install-info --entry="* $f (foo): $f" $f /usr/share/info/dir
> 
> but I don't have the full context for where $f is being defined for why
> it is sometimes expanded in make and others by the shell.

It's not a Makefile snippet; it's a snippet from a bash shell script.  Here's more context:

  for f in /usr/share/info/*; do
      case "$f" in
          *\**)
              ;;
          */dir|*/dir.info*)
              ;;
          *-[0123456789]*)
              ;;
          *)
              install-info $f /usr/share/info/dir ||
              install-info --entry="* $$f ($f): $$f" $$f /usr/share/info/dir
              ;;
      esac
  done

It looks to me like all those double dollar signs will just get expanded to the PID of the bash process, so that the second install-info command is nonsense.  But maybe I'm missing something.

Ken


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]