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RE: type -p return status is 0 if alias found


From: John.Wiersba
Subject: RE: type -p return status is 0 if alias found
Date: Wed, 4 Apr 2007 13:00:11 -0400

Thanks for your reply, Mike!

Here's what I'm reading in the man page:

type [-aftpP] name [name ...]
       With no options, indicate how each name would be interpreted  if
       used as a command name.  If the -t option is used, type prints a
       string which is one of alias,  keyword,  function,  builtin,  or
       file  if  name  is  an  alias,  shell  reserved  word, function,
       builtin, or disk file, respectively.  If the name is not  found,
       then  nothing  is  printed,  and  an  exit  status  of  false is
       returned.  If the -p option is used,  type  either  returns  the
       name of the disk file that would be executed if name were speci-
       fied as a command name, or nothing if ``type -t name'' would not
       return  file.  The -P option forces a PATH search for each name,
       even if ``type -t name'' would not return file.  If a command is
       hashed,  -p  and  -P print the hashed value, not necessarily the
       file that appears first in PATH.  If the -a option is used, type
       prints  all of the places that contain an executable named name.
       This includes aliases and functions,  if  and  only  if  the  -p
       option  is  not  also used.  The table of hashed commands is not
       consulted when using -a.  The -f option suppresses  shell  func-
       tion  lookup, as with the command builtin.  type returns true if
       any of the arguments are found, false if none are found.

I can see that you're interpreting the last sentence to mean:  type -p
NAME found NAME and therefore it returned true.  But since it was not a
"file" (according to type -t NAME), then it didn't print anything.

Maybe this is the only distinction between -p and -P (it's hard to tell
because of the way it's worded)?  If so, then it would be clearer to
state it directly with something like:  The -P option is like the -p
option.  However the -P option returns true iff ``type -t name'' would
print ``file'', whereas the -p option returns true iff ``type -t name''
would return true.

Is there any other distinction between -p and -P?  It certainly
surprised me to see that -p printed nothing but returned true.  Was that
the reason -P was created -- to bring the return value in line with the
output?

Thanks!
-- John Wiersba

> -----Original Message-----
> From: Mike Frysinger [mailto:address@hidden 
> Sent: Wednesday, April 04, 2007 12:25 PM
> To: address@hidden
> Cc: Wiersba, John (TH USA)
> Subject: Re: type -p return status is 0 if alias found
> 
> On Tuesday 03 April 2007, address@hidden wrote:
> >    "type -p CMD" normally has a non-zero return status if CMD is not
> > found.  But if CMD is an alias, the return status is zero 
> even though
> > nothing is printed to stdout.
> 
> by definition, this is how -p is supposed to work ... my 
> guess is you want -P
> -mike
> 




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