From: Peter Stephenson <pws@ibmth.df.unipi.it>
To: zsh-workers@math.gatech.edu
Subject: PATCH: 3.1.5: eval with exported vars
Date: Fri, 11 Dec 1998 10:52:46 +0100 [thread overview]
Message-ID: <9812110952.AA23579@ibmth.df.unipi.it> (raw)
In-Reply-To: "Phil Pennock"'s message of "Fri, 11 Dec 1998 08:05:58 NFT." <19981211080558.46630@athenaeum.demon.co.uk>
Phil Pennock wrote:
> Trying this:
> % FOO=x eval sh -c 'echo $FOO'
> and then without the eval, it seems the eval loses the auto-export
> functionality, in both 3.0.5 and 3.1.5. It doesn't appear to be
> documented though.
The workaround is
eval 'FOO=x sh -c '\'echo $FOO'\'
by the way. (Note all the quotes: see below.)
> Bug?
I was going to say yes, but it's specifically mentioned in the source
that it does this (exec.c, line 1793 of my current version):
if (cmd->vars) {
/* Export this if the command is a shell function,
* but not if it's a builtin.
*/
addvars(cmd->vars, is_shfunc);
I think the idea must have been that `builtins don't need values
exported' which, as you've seen, is not true in this case. The patch
is the simplest fix, and I think it's good enough.
There's something that had me horribly confused (though it's actually
working the way God intended):
% FOO=x eval sh -c 'echo $FOO'
<nothing printed>
That's because eval sees the string "sh -c echo $FOO" and turns this
into sh -c 'echo' 'x', so sh gets an 'echo' command with $0 set to x.
To prove it:
% FOO=x eval sh -c '"echo \$0" $FOO'
x
(why $0 not $1?) so you really need
% FOO=x eval sh -c \''echo $FOO'\'
x
phew.
*** Src/exec.c.eval Thu Dec 10 11:24:46 1998
--- Src/exec.c Fri Dec 11 10:14:01 1998
***************
*** 1792,1800 ****
if (cmd->vars) {
/* Export this if the command is a shell function,
! * but not if it's a builtin.
*/
! addvars(cmd->vars, is_shfunc);
if (errflag) {
restore_params(restorelist, removelist);
lastval = 1;
--- 1792,1802 ----
if (cmd->vars) {
/* Export this if the command is a shell function,
! * but not if it's a builtin, unless the builtin
! * is an eval.
*/
! addvars(cmd->vars, is_shfunc ||
! (is_builtin && ((Builtin)hn)->funcid == BIN_EVAL));
if (errflag) {
restore_params(restorelist, removelist);
lastval = 1;
Peter Stephenson <pws@ibmth.df.unipi.it> Tel: +39 050 844536
WWW: http://www.ifh.de/~pws/
Dipartimento di Fisica, Via Buonarroti 2, 56127 Pisa, Italy
next parent reply other threads:[~1998-12-11 10:11 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <19981211080558.46630@athenaeum.demon.co.uk>
1998-12-11 9:52 ` Peter Stephenson [this message]
1998-12-11 12:23 ` Andrej Borsenkow
1998-12-11 12:45 ` Peter Stephenson
1998-12-11 13:27 ` Andrej Borsenkow
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