__DATA__ on commandline does not work?

Skeeve has asked for the wisdom of the Perl Monks concerning the following question:

Hi! I just noticed that this, entered on the commandline (bash / OS X 10.5) dos not work:

perl -e 'print <DATA>;
__DATA__
line 1
line 2
'
[download]

Whereas this similar code works:

perl <<'XXX'
print <DATA>;
__DATA__
line 1
line 2
XXX
[download]

Can someone explain why the first version does not work?

s$$([},&%#}/&/]+}%&{})*;#$&&s&&$^X.($'^"%]=\&(|?*{%
+.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e

Comment on __DATA__ on commandline does not work? Select or Download Code

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Re: __DATA__ on commandline does not work? by ikegami (Patriarch) on Apr 10, 2010 at 20:09 UTC
`DATA` is the handle from which Perl reads the source. No handle is used for `-e`, so no `DATA`.	[reply] [d/l] [select]
Re: __DATA__ on commandline does not work? by The Perlman (Scribe) on Apr 10, 2010 at 19:17 UTC
IIRC the `-e` switch means eval, and IMHO you cant use __DATA__ in eval. The second form you showed is completely different since you are using a shell (bash?) here-doc which is similar to execute a file. Anyway there is no big point in using __DATA__ within `-e'...'` since the shell offers plenty of possibilities to pipe the data into your snippet. for instance `perl -e'print <>' <<XXX > 1 > 2 > 3 > XXX 1 2 3` [download]	[reply] [d/l] [select]
Re: __DATA__ on commandline does not work? by repellent (Priest) on Apr 10, 2010 at 20:11 UTC
Here's a way that works without `-e` for Unix shells: `$ perl print <DATA>; __DATA__ line 1 line 2 ^D line 1 line 2` [download] Hit Ctrl-D at `^D`.	[reply] [d/l] [select]
Re^2: __DATA__ on commandline does not work? by cdarke (Prior) on Apr 11, 2010 at 14:24 UTC
Expanding that to use a here doc.: `#!/bin/bash perl << HDEND print <DATA>; __DATA__ line 1 line 2 HDEND` [download]	[reply] [d/l]
Re^3: __DATA__ on commandline does not work? by Skeeve (Parson) on Apr 11, 2010 at 18:51 UTC
...which s almost exactly my second codefragment in the question. `s$$([},&%#}/&/]+}%&{});#$&&s&&$^X.($'^"%]=\&(\|?{%` `+`.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e	[reply] [d/l] [select]
Re: __DATA__ on commandline does not work? by afoken (Chancellor) on Apr 10, 2010 at 18:19 UTC
I know that perl reads its code from STDIN in the second case, STDIN is connected to a pipe filled by the shell. So you have a working file handle. I guess that in the first case, the -e argument is stuffed directly into the parser, no real file handle, thus no DATA file handle, so no output. Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply]
Re: __DATA__ on commandline does not work? by pid (Monk) on Apr 12, 2010 at 09:05 UTC
Hi Skeeve, I've tried this: $ perl -MO=Deparse -wle 'print <DATA>; __DATA__ Text HERE' BEGIN { $^W = 1; } BEGIN { $/ = "\n"; $\ = "\n"; } print <DATA>; __DATA__ -e syntax OK And it seems perl tends to ignore the "`Text HERE`" part. Hope this helps a bit. :)	[reply] [d/l]