Technically, this is more of a shell question than a perl question. That said, I can understand that it is highly relevant to perl programmers since we seem to take huge pride in our one-liners. ;-)

For Bourne-shell and derivitives (such as ksh and bash), you simply need to put your program in single quotes, and not use single quotes inside your program.

I think it's the same for C-shell, but I'm not really a C-shell expert.

For CMD.EXE (both Win32 and OS/2), you need to use double quotes, and not use double quotes inside your program. Since double quotes interpolate everything, you may want to. Don't - use $/ instead of "\n", e.g., perl -e "print 'foo', $/". For other interpolation, use qq, e.g., perl -e "print qq(foo\n)". You also want to be careful with percent signs - avoid them if you can. If you can't, I think doubling them works - %% probably is replaced with a single %.

I'm sure others will expand on this - but I've not had any need of more than this. I rarely use Windows, and when I have to, I don't need to do any modulos or print percent signs.

#!/usr/bin/perl
# one_liner - produce a perl one-liner out of perl code
use Sysadm::Install qw(:all);
my $in = join "", <>;
$in =~ s/\n/ /g;
print "perl -e ", qquote($in, ':shell'), "\n";
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Now, if you call one_liner without arguments, it'll wait for code to be typed into STDIN, terminated by CTRL-D, and spit out the one-liner right after:

$ one_liner
print "hello\n";
print "world\n";
^D

perl -e "print \"hello\\n\"; print \"world\\n\"; "
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Produces properly escaped one-liners out of any messy perl code you paste in.

print chr(047)
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For instance, to single-quote something in bash:

perl -we'my $c=400; print q(not interpolated: $c)'

This is even more useful in Win32, where you need to avoid the much more common doublequotes:

perl -we"my $c=400; print qq(interpolated: $c)"

You can also delimit on something besides parentheses, but parens are easy to read and not disallowed by anything, so I rarely bother.

See perlop under q/STRING/.

The particular characters that you need to escape are dependent upon the shell, not on perl. For the most part, you can just encase the perl string to be evaluated in single quotes in a unix shell, and make sure that you don't use single quotes in your perl. (I don't know about windows quoting) :

You can also use -l (that's a lower case L), so you can send a command quickly without the shell messing with it. (but again, this won't work in the times when you want the shell to do its magic, and it also keeps you from using the shell's abilities to repeat the command).

If there are times when you want to use shell variables in your line, you can either export them and reference them in perl as $ENV{"NAME"} rather than $NAME or you can end the quoting, use the variable, and then start it back up again:

perl -e 'print "you are logged in as $ENV{USER}\n";'
perl -e 'print "you are logged in as '$USER'\n";'
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The only thing that's really tricky is when you're trying to mix perl and shell commands ... which I'd advise not doing from the shell, as you can't always be sure of the output, and calling it from within perl.

perl -e 'printf( qq(%s\n"),
 q("This is a string @#$%^%&*/\\) . q[()] . chr(047) . qq("))'
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The bottom line is that you have to read your shell's manpage. If you don't like what you read, switch shells. If you can't switch shells, well, grumble, and deal with what you've got.

The best reference I can give you is to type "man <your_shell_name_here>".