mvp@v7fs1.UUCP (arf) (01/18/89)
Some time ago I asked about how a csh script could change
global environment variables. Thanks to everyone who responded.
Here's a summary:
You can't do it, and this question should be added to the
"List of Most Frequently Asked Questions".
At least, there's no official way, because to do that requires a
child to change its parent's environment, and that's a no-no. A
couple of messages implied that it might be possible, if one were
to play some "Real Programmer" type games. Many replies also
said that if I wanted to call a script to set some environment
variables, I should either "source" the script ( . in sh) or
create an alias. (I had ruled out sourcing the script because
you can't pass arguments to a sourced script.)
chris@mimsy.UUCP (Chris Torek) suggested a script which
generates and then prints the desired setenv command on standard
output, and an alias
> % alias edit-env 'eval `~/bin/edit-env`'
to make the current shell do the actual setenv. This works
fine, but doesn't work for the specific problem I was trying to
solve -- a script which saves its argument list, and if called
with no arguments, uses the old argument list. (Perhaps I
should have specified what I was trying to do more exactly.)
The way I finally kludged it was more along the lines of
if $#argv > 0 then
echo $* >~/.last-parms
endif
program-call `cat ~/.last-parms`
--
Mike Van Pelt "Hey, hey, ho ho,
Video 7 Western culture's got to go."
...ames!vsi1!v7fs1!mvp Stanford students and faculty.djk@munnari.oz (David James Keegel) (01/22/89)
in article <186@v7fs1.UUCP>, mvp@v7fs1.UUCP (arf) says:
]
] Some time ago I asked about how a csh script could change
] global environment variables. Thanks to everyone who responded.
] ...
] [Chris Torek's suggestion] works
] fine, but doesn't work for the specific problem I was trying to
] solve -- a script which saves its argument list, and if called
] with no arguments, uses the old argument list. (Perhaps I
] should have specified what I was trying to do more exactly.)
Yes, you should. A general solution for this is hard, a specific one
is reasonably easy.
] The way I finally kludged it was more along the lines of
]
] if $#argv > 0 then
] echo $* >~/.last-parms
] endif
] program-call `cat ~/.last-parms`
I deduce from this that you are using C-shell.
Well, my .cshrc contains the following:
alias to 'set to=\!^; \to' \!^ "'\!:2*'"
alias ot '\to "$to"' "'\!*'"
There is a horrible confusion of quotes and backslashes here, but the point
is that when I run `to' (usage: "to user message ..."; like "echo message |
write user"), it saves the user name in the variable $to, and I can use
"ot" to recover it. So these are equivalent:
% to fred hi there % to fred hi there
% to fred how are you % ot how are you
If you don't like the waste of file space from the shell script and
~/.last-parms, and you can be bothered, you feel free to adapt this idea.
--
David Keegel (djk@munnari.oz)
"Flattery will get you nowhere, unless someone else does it to you"