strange shell behavior...thoughts?

[Gordon Messmer]

Kevin Martin wrote:
> So I'm fairly confused at this point.
> Start with a /bin/sh shell.
> Then do:
> 
> sh-3.2$ unset $?
> sh: unset: `0': not a valid identifier

You mean "unset ?".  That's not to say that it'll work, but when you 
unset variables, you don't precede them with the $ character.

> ok, no problem; then do
> 
> sh-3.2$ /bin/ksh -c " set -xv  ; grep ABCD  b ; echo $? ; if [ "$?" =
> "0" ] ; then echo yes ; fi"
> + grep ABCD b
> ABCD="C" ; export ABCD
> + echo 1
> 1
> + [ 1 = 0 ]
> 
> WHAT? 

If you want to understand what's going on, try:

$ false
$ echo "set -xv  ; grep ABCD  b ; echo $? ; if [ "$?" ="0" ] ; then echo 
yes ; fi"

If you want to pass "$" characters like that, you'll need to escape them 
or use single quotes:

$ ksh -c " set -xv  ; grep ABCD  b ; echo \$? ; if [ \"\$?\" =\"0\" ] ; 
then echo yes ; fi"

$ ksh -c ' set -xv  ; grep ABCD  b ; echo $? ; if [ "$?" ="0" ] ; then 
echo yes ; fi'