Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!pdi.UUCP!shoshana
From: shoshana@pdi.UUCP (Shoshana Abrass)
Newsgroups: comp.sys.sgi
Subject: Re: awk question...
Message-ID: <9006111926.AA7340126@pdi.UUCP>
Date: 11 Jun 90 19:26:43 GMT
Sender: usenet@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 31

> I'm writting a script in which a variable takes the value of a
> userid.  I then want to find out who this userid refers to.
>
> I want to do that in one line, involving awk (I know how to do it
> using multiple lines of code).
>
> BUT 123 is the content of a variable, say UID.  The following does
> NOT work:
>
>     awk -F: '$3 == $UID {print $1}' /etc/passwd

  The problem is that you are trying to access a shell variable from
  within an awk script -- since awk has its own 'variable space', it
  thinks that UID isn't set. You can set awk variables on the command
  line, with this general syntax:

        awk 'commands' var=text filename

  Thus your example would become:

        awk -F: '$3 == AWK_UID {print $1}' AWK_UID=$UID /etc/passwd
                     ^^^     ^^^
  Notice the lack of both the $ sign and the double-quotes around
  AWK_UID. 

  Good luck! I know I found this in the awk book somewhere, but I
  can't find the page now or I'd refer you to it.....

  -shoshana
  Shoshana Abrass
  pdi!shoshana@sgi.sgi.com