Set case sensitive Windows environment variables in Perl - windows

Question

I am trying to set some Windows environment variables in Perl with case sensitivity in order to use them in a shell script.
However, I noticed that the environment variables are all in uppercase when I try to use them in lowercase in a shell script called from Perl with system command and run with Msys.
For example, the following script:
#!perl
system "echo echo TOTO=\$TOTO > toto.sh";
system "echo echo Titi=\$Titi >> toto.sh";
system "echo echo TITI=\$TITI >> toto.sh";
$ENV{'TOTO'}="0+0";
$ENV{'Titi'}="Not toto!";
system("sh toto.sh");
returns (while run in Msys) the following output:
TOTO=0+0
Titi=
TITI=Not toto!
Does anybody know whether this is possible in Windows (i.e. how to set the environment variable Titi and not TITI)?
Thanks

Answer 1

Windows environment variable identifiers are case-independent in the same way as Windows files.
Titi and TITI are both names for the same variable, and its value can be acccessed through either $ENV{TITI} or $ENV{Titi} in Perl. Likewise echo %TITI% and echo %Titi% on the command line will give the same result.
If you explain why it is that you need case-sensitive environment variable names then we may be able to help you.

Answer 2

The following should apply independently of the casing problem.
Let's take the first line:
system "echo echo TOTO=\$TOTO > toto.sh";
If you call
echo echo TOTO=\$TOTO
on your command line, the output will be:
echo TOTO=\$TOTO
which seems to be, what you want.
However, the line you are calling with system is first interpreted by perl, so your escaped \$ becomes a $.
The output then depends on the current value of $TOTO (before you set the environment variable in the script), which is probably empty.
You should change all those system calls to be single quoted:
system 'echo echo TOTO=\$TOTO > toto.sh';
If you do this, you will get the following output:
TOTO=0+0
Titi=
TITI=not TOTO
Titi is empty, because you didn't assign a value to it.

Answer 3

It appeared to be that it is not possible to do: Windows will only use the uppercase variables.
The way I did was to temporarily transform the script by replacing variables with their upper-case equivalent and switch them back to the previous state after using them.
In my case, I had to deal with the variables exported from the shell script Run_Session.sh. I have created a Perl script to perform the uppercase replacement and this is the result.
###############################
## SUBROUTINE uc_variables ##
#-----------------------------#
# This subroutine convert the environment variables exported
# by the top level script to upper case, and can revert the operation.
#
# Input:
# -----
# $mode: "ON" (default) or "OFF"
#
# Output:
# ------
# N/A
#-----------------------#
#########################
sub uc_variables {
my $mode=shift;
chdir $Bin;
if ($mode eq "OFF") {
foreach my $bak (glob "{*,*/*}.sh.bak") {
(my $orig = $bak)=~s/\.bak//;
move($bak,$orig);
}
} else {
#Check if back-up already exists
uc_variables("OFF") if (-e "Run_Session.sh.bak");
#List variables to update
my %uc_var;
open RUN_SESSION,"<Run_Session.sh" or die "Error while reading Run_Session.sh ($!)\n";
map { /export\s+(\w*[a-z]\w*)/ and ($uc_var{$1}=uc($1))=~s/Directory/DIR/i } <RUN_SESSION>;
close RUN_SESSION;
#Replace variables
foreach my $shell (glob "{*,*/*}.sh") {
#Back-up
copy($shell,"$shell.bak");
#Read data
open SHELL,"<$shell" or die "Error while reading $shell ($!)\n";
my $SHELL = join("", <SHELL>);
close SHELL;
#Replace
map { $SHELL=~s/$_/$uc_var{$_}/g } keys %uc_var;
#Print
open SHELL,">$shell" or die "Error while writing in $shell ($!)\n";
print SHELL $SHELL;
close SHELL;
}
}
} #end of uc_variables