[lug] alias or another trick

[Jeffrey S. Haemer]

Davide,

If I understand your question, I agree with Will and Rob. Here's an
illustration that illustrates:

#!/bin/bash -ex

# _xlc=$(which xlC)
#xlC() { [ "$1" = "cc_r" ] && shift; $x $*;}
_date=$( which date );
date() { [ "$1" = "cc_r" ] && shift; $_date $*;  }

date
date +%Y
date cc_r +%Y


(I save off the original meaning because, unlike aliases, functions will
recurse.)

Backing off a step, bash aliases are only meant to be interactive typing
shortcuts.  Without special pleading, they won't even work inside scripts.
 Running this script

#!/bin/bash
alias a="echo foo"
a

will get you

line 3: a: command not found


As the bash man page says,


The rules concerning the definition and use of aliases are  somewhat
 confusing.
[...]
For almost every purpose, aliases are superseded by shell functions.


On Sat, Dec 24, 2011 at 12:45 PM, Davide Del Vento <
davide.del.vento at gmail.com> wrote:

> Hi all,
> I have a script (more on it later) that is compiling a program. It
> needs to use two different compilers, namely cc_r and xlC. The problem
> is that it has a problem in the way it invokes xlC. It does:
>
> xlC cc_r <rest-of-the-compiler-arguments>
>
> I was hoping to fix it with something like
>
> alias "xlC cc_r"=xlC
>
> But of course aliases cannot contain spaces (at least in bash on AIX -
> sorry this isn't a pure-Linux question). Now, the right answer is "fix
> the script", but this is not feasible - the script is python's
> distutils and is untouchable and unfixable (today is your lucky day:
> I'll spare the long rant on this subject :-)
>
> An easier trick could be do alias cc_r to nothing, but I can't do
> that, since there are other (previous) calls which invoke cc_r alone -
> and that part works (after I fixed several other issues, don't think
> that it works out of the box :-)
>
> And by the way, distutils isn't like make (which doesn't recompile
> stuff that's already compiled): it recompiles everything, any time is
> re-run. So running once, then alias cc_r to nothing and run again will
> not work.
>
> Does anybody have a suggestion on how to fool it? What I would do at
> this time is write a script, call it xlC, put it somewhere in the path
> earlier than the actual xlC, and use it as "middleman" to the actual
> xlC removing the broken cc_r argument (if any). This would work, but
> since I'm writing a script to pass to other people for doing this
> installation, it's a little too dirty and requires an additional file
> (I know I can do it with an herefile, and I would, but still it's
> dirtier than the one-liner alias would be).
>
> Thanks and Merry Christmas!
> Davide
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-- 
Jeffrey Haemer <jeffrey.haemer at gmail.com>
720-837-8908 [cell], http://seejeffrun.blogspot.com [blog],
http://www.youtube.com/user/goyishekop [vlog]
*פרייהייט? דאס איז יאַנג דינען וואָרט.*
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