Re: What am I doing wrong here?

:> Due to odd quoting rules, I suggest using ""
on Windows, and '' on 
UNIX. Choose to use qq() or q() instead of escaping for
either.

Well, not trying to inflame the winx v *nix wars soYMMV but
I've always 
had troubles getting command line scripts to run in cmd.exe
C:Documents and Settingsandy>perl -e 'print("Hello
world.n");'

C:Documents and Settingsandy>
C:Documents and Settingsandy>perl -e
"print("Hello world.n");"
Hello world.

C:Documents and Settingsandy>perl -e "print
qq(Hello world.n);"
Hello world.

Cutnpasted all 3 there produce the appropriate result on
linux.
On *nix you can actually do multi-line programs from the
command line, 
as a <Enter> inside of surrounding quotes doesn't end
the command
# perl -e 'print "hello worldn";
print "goodbye quotesn";
print "even in the
tquoten";
'
hello world
goodbye quotes
even in the
        quote
#

A different issue on *nix is '$' interpolation.  This works
on winx 
(note dbl quotes script surrounders):
perl -e "$hi = qq(Hello world.n); print $hi"

but fails in linux as '$hi' gets replaced by whatever's in
the shell's 
'$hi' env var, probably nothing:
# perl -e "$hi = qq(Hello world.n); print $hi"
syntax error at -e line 1, near "="
Execution of -e aborted due to compilation errors.

perl see's a script like:
= qq(Hello world.n); print

You need to use single quotes to protect the program from
being interpolated
# perl -e '$hi = qq(Hello world.n); print $hi'
Hello world.

That one gets a different error on winx
C:Documents and Settingsandy>perl -e '$hi = qq(Hello
world.n); print $hi'
Can't find string terminator "'" anywhere before
EOF at -e line 1.

I think the semicolon acts as a line ending or comment,
maybe?  But this 
is the sort of error that made me give up on winx cmd lines
scripting.

a
_______________________________________________
ActivePerl mailing list
ActivePerllistserv.ActiveState.com
To unsubscribe: http:/
/listserv.ActiveState.com/mailman/mysubs

Andy Bach wrote:
> 
> That one gets a different error on winx

You mean cmd.exe - not win32.  I run tcsh on Win32 with no
such problem.

> C:Documents and Settingsandy>perl -e '$hi =
qq(Hello world.n); print $hi'
> Can't find string terminator "'" anywhere
before EOF at -e line 1.
 >
> I think the semicolon acts as a line ending or comment,
maybe?  But this 
> is the sort of error that made me give up on winx cmd
lines scripting.

Again - it's all about what shell you use.  Try a native
port of tcsh or
bash - you'll seldom use cmd.exe again.

_______________________________________________
ActivePerl mailing list
ActivePerllistserv.ActiveState.com
To unsubscribe: http:/
/listserv.ActiveState.com/mailman/mysubs

Andy Bach wrote:
> :> Due to odd quoting rules, I suggest using
"" on Windows, and '' on 
> UNIX. Choose to use qq() or q() instead of escaping for
either.
> Well, not trying to inflame the winx v *nix wars soYMMV
but I've 
> always had troubles getting command line scripts to run
in cmd.exe
> C:Documents and Settingsandy>perl -e
'print("Hello world.n");'
The rules are different. Even on UNIX, CSH vs SH is
different. Try 
adding ! into your command line from CSH and see confusing
results... 

    csh> perl -e 'print !1'
    1: Event not found.

It isn't UNIX vs Windows as much as knowing the rules of the
shell you 
are using.

For Windows, the rules are pretty simple. The only
recognized quotes are 
double quotes (""). Backslashes within quotes are
passed through unless 
an odd number of backslashes precede the closing double
quote, in which 
case, the double quote is considered escaped. If a
%VARIABLE% occurs 
anywhere in the string it is substituted with the
environment variable 
that it matches.

I'm too tired right now to describe the UNIX rules. CSH vs
SH vs KSH vs 
ZSH vs ... they are all slightly different.

Storing the script to a file is definitely best.

> A different issue on *nix is '$' interpolation.  This
works on winx 
> (note dbl quotes script surrounders):
> perl -e "$hi = qq(Hello world.n); print
$hi"

Try:
    C:> perl -e "print %PATH%, qq(n)"

Granted, %PATH% is less likely to be used in a Perl command
line - but 
the point remains that interpolation is a problem no matter
which shell 
you use. 

> That one gets a different error on winx
> C:Documents and Settingsandy>perl -e '$hi =
qq(Hello world.n); 
> print $hi'
> Can't find string terminator "'" anywhere
before EOF at -e line 1.
> I think the semicolon acts as a line ending or comment,
maybe?  But 
> this is the sort of error that made me give up on winx
cmd lines 
> scripting.

The history here is that cmd.exe has odd interpretation
rules. First 
off, cmd.exe does not know much about quotes, and definately
knows 
nothing about single quotes (''). As far as cmd.exe is
concerned, you 
are calling:
    perl -e "'$hi" "="
"qq(Hello" "world.n)"; print
"$hi'"

On Windows, however, the calling shell (cmd.exe) does not
break the 
arguments up into argv. Instead, it passes the entire
command line (up 
to the newline or semicolon or a few other characters) to
the program as 
a single string. It is then up the program to break up the
arguments as 
it sees fit. Perl is based on Windows libc which emulates
argv splitting 
according to UNIX rules.

The effect of this is that you have cmd.exe using one set of
rules, and 
then perl.exe using a different set of rules. Where the
rules are 
compatible, behaviour is "expected". Where the
rules are incompatible, 
people can easily become confused if they do not know both
rules.

Places where this can be a problem? Try doing shell globbing
on Windows 
and be confused as to why:

    C:> perl test.pl *.txt

Does not always work. CMD.EXE doesn't expand *.txt. This is
up to the 
program - perl.exe. If perl.exe does not expand it? It
doesn't get expanded.

Some fun information for people to think about... 

Cheers,
mark

-- 
Mark Mielke <markmielke.cc>
_______________________________________________
ActivePerl mailing list
ActivePerllistserv.ActiveState.com
To unsubscribe: http:/
/listserv.ActiveState.com/mailman/mysubs