'^' acts an escape character on the CMD command line, a little like '\' under unix, but much more limited. The only characters that it escapes are a few characters that the CLI otherwise treats specially.

These are  | < > % ^

Used, outside of double quotes, it prevents the command line from treating these characters as pipes, io-redirection or the start of an environment variable substitution respectively, as well as escaping itself.

A simple demonstration.

P:\test>perl -e"print qq[($_)] for @ARGV" ^| ^< ^> ^% ^^
(|)(<)(>)(%)(^)
[download]

Also like '\', it can be used as a line-continuation character.

C:\>echo hi the^
More? re
hi there
[download]

My understanding is that this behaviour is undocumented. Did you find this out by experimentation or did you manage to unearth something from MSN that nobody else I know of has found?

Incidentally, I have a patch for the README.win32 (which is automatically converted to perlwin32.pod when perl is built) that expands on the explanation of quoting rules (that I figured out by experimentation), perhaps you and I should knock together a better patch and get it included? The doc currently mentions ^ but doesn't explain it as well as you did (IMO).



---
demerphq



First they ignore you, then they laugh at you, then they fight you, then you win.
-- Gandhi

Essentially, it is the result of experimentation and as such subject to the whims of change by MS. It has been consistant (if ecclectic) for a good while now though.

If you want to add that to your patch I'm all for it.

The harder one is working out the treatment of double quotes...

P:\test>perl -le"print qq[($_)] for @ARGV" "fred"""" """""bill"
(fred")
("bill)

P:\test>perl -le"print qq[($_)] for @ARGV" "fred" "bill"
(fred)
(bill)

P:\test>perl -le"print qq[($_)] for @ARGV" "fred"" "bill"
(fred")
(bill)

P:\test>perl -le"print qq[($_)] for @ARGV" "fred"" ""bill"
(fred")
(bill)

P:\test>perl -le"print qq[($_)] for @ARGV" "fred"" """bill"
(fred")
("bill)

P:\test>perl -le"print qq[($_)] for @ARGV" "fred""" """bill"
(fred" "bill)

P:\test>perl -le"print qq[($_)] for @ARGV" "fred""a" ""a"bill"
(fred"a "abill)

P:\test>perl -le"print qq[($_)] for @ARGV" "fred"a"" "a""bill"
(freda)
(a"bill)
[download]

If you can discern a pattern in that lot, I've several hundred more weird examples for analysis:)

---

Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"Think for yourself!" - Abigail
Hooray!

(my $copy = $ARGV[0]) =~ s/([^[:print:]])/sprintf " (0x%02x) ", ord $1
+/ge;
print $copy;
[download]

The above piece of code can help you figure out windows' interpretation of what you keyed. It prints all the non-printable chars as hex.

For example, if you punch "Ctrl-^" "w", which appears on your screen as "^^w" (I guess that's how you get it), this program tells you window takes that "Ctrl-^" as 0x1e.

Update:

At one point, I had the same thought as BrowserUK, that ^ is an escape char, but after I tested on my PC, it does not behave like that... so not all versions. (well I am still running win98)

Indeed. I should have emphasised the CMD.EXE.

Win95/98 (I'm not sure about ME) all use COMMAND.COM as their CLI, which has a completely different set of (equally unwritten:) rules.

---

Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"Think for yourself!" - Abigail
Hooray!

Thanks, pg. But I didn't "key" or "punch" anything. I just typed "^" (shift-6).

I'll investigate this some more.

--dda