Beefy Boxes and Bandwidth Generously Provided by pair Networks
go ahead... be a heretic
 
PerlMonks  

Re: Uncommon* but Useful Perl Command Line Options (for one-liners)

by ysth (Canon)
on Jan 29, 2004 at 01:51 UTC ( #324858=note: print w/ replies, xml ) Need Help??


in reply to Uncommon* but Useful Perl Command Line Options for One-liners

so dealing with files originating from other OS needs the ability to change the value of \n
I would say "to change the value of $/". -0 certainly doesn't change \n.

There are also some funky details about how -0 works. First of all, -0[octal] is limited to 3 following octal digits. Anything beyond that is interpreted as a new bundled switch (e.g. -07770 is equivalent to -0777 -0 (which is equivalent to just -0)).

-0 with no following octal digits will set $/ to "\0", the null character. As you say, -00 does paragraph mode ($/ = "") instead. This applies to -000 and -0000 also; as above, -00000 etc is interpreted as two separate switches where the first is meaningless, creating the pleasant cycle:
switcheffect
-0\0 record separator
-00paragraph mode
-000paragraph mode
-0000paragraph mode
-00000\0 record separator
-000000paragraph mode
-0000000paragraph mode
-00000000paragraph mode
-000000000\0 record separator
-0000000000paragraph mode

Not just -0777, but any attempt to specify an octal character greater than 0377 (255 decimal), will trigger slurp mode.

And starting with 5.8.1, -0 will allow hex characters to be specified like -0x1ff (but you can't bundle it with other switches like -0x1ffw; for backward compatibility, that is interpreted as -0 -x1ffw instead of -0x1ff -w (see perlrun for details on the -x switch)). Any number of hexidecimal digits are permitted, but only the low 32-bits are used. This allows specifying any unicode character as the record separator. Paragraph mode or slurp mode cannot be specified with -0x; -0x0 sets $/ to "\0", not "", -0x1ff (the "equivalent" of -0777) sets $/ to "\x{1ff}", not undef.

-0x actually allows an extra "x" or "0x" after the first one (e.g. -0x0x0d or -0xx0); this can be construed as a bug.


Comment on Re: Uncommon* but Useful Perl Command Line Options (for one-liners)

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://324858]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others wandering the Monastery: (7)
As of 2015-07-04 21:47 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









    Results (60 votes), past polls