01-07-2012
Quote:
Originally Posted by
LessNux
The delimiter can be changed from space to other characters by setting $IFS. However, I would rather stick on space for delimiter, because all characters including all symbols seem to be legal for file names or path names on modern GUI OS's.
Even a LF (\n, 0x0A) can be in file names on GUI OS's. Though it may be silly to put LF's in file names, it can accidentally happen when one copies from text and pastes it to a file name.
I thought about setting the delimiter to a non-printable character that is really unusual, such as ETX (0x03), ACK (0x06). However, it would be difficult for the user to input such non-printable characters at the read's prompt. I would like to let the user enter file names as he/she would enter on command line.
I discourage any attempts that resort to IFS.
The real problem is that the "read" command does not understand quotes and backslashes as the shell does. What the "read" command has obtained needs to be re-parsed by correctly handling quotes and backslashes like the shell. Can you think about any technique for such re-parsing?
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LEARN ABOUT DEBIAN
text::parsewords
Text::ParseWords(3perl) Perl Programmers Reference Guide Text::ParseWords(3perl)
NAME
Text::ParseWords - parse text into an array of tokens or array of arrays
SYNOPSIS
use Text::ParseWords;
@lists = nested_quotewords($delim, $keep, @lines);
@words = quotewords($delim, $keep, @lines);
@words = shellwords(@lines);
@words = parse_line($delim, $keep, $line);
@words = old_shellwords(@lines); # DEPRECATED!
DESCRIPTION
The &nested_quotewords() and "ewords() functions accept a delimiter (which can be a regular expression) and a list of lines and then
breaks those lines up into a list of words ignoring delimiters that appear inside quotes. "ewords() returns all of the tokens in a
single long list, while &nested_quotewords() returns a list of token lists corresponding to the elements of @lines. &parse_line() does
tokenizing on a single string. The &*quotewords() functions simply call &parse_line(), so if you're only splitting one line you can call
&parse_line() directly and save a function call.
The $keep argument is a boolean flag. If true, then the tokens are split on the specified delimiter, but all other characters (quotes,
backslashes, etc.) are kept in the tokens. If $keep is false then the &*quotewords() functions remove all quotes and backslashes that are
not themselves backslash-escaped or inside of single quotes (i.e., "ewords() tries to interpret these characters just like the Bourne
shell). NB: these semantics are significantly different from the original version of this module shipped with Perl 5.000 through 5.004.
As an additional feature, $keep may be the keyword "delimiters" which causes the functions to preserve the delimiters in each string as
tokens in the token lists, in addition to preserving quote and backslash characters.
&shellwords() is written as a special case of "ewords(), and it does token parsing with whitespace as a delimiter-- similar to most
Unix shells.
EXAMPLES
The sample program:
use Text::ParseWords;
@words = quotewords('s+', 0, q{this is "a test" of quotewords "for you});
$i = 0;
foreach (@words) {
print "$i: <$_>
";
$i++;
}
produces:
0: <this>
1: <is>
2: <a test>
3: <of quotewords>
4: <"for>
5: <you>
demonstrating:
0 a simple word
1 multiple spaces are skipped because of our $delim
2 use of quotes to include a space in a word
3 use of a backslash to include a space in a word
4 use of a backslash to remove the special meaning of a double-quote
5 another simple word (note the lack of effect of the backslashed double-quote)
Replacing "quotewords('s+', 0, q{this is...})" with "shellwords(q{this is...})" is a simpler way to accomplish the same thing.
AUTHORS
Maintainer: Alexandr Ciornii <alexchornyATgmail.com>.
Previous maintainer: Hal Pomeranz <pomeranz@netcom.com>, 1994-1997 (Original author unknown). Much of the code for &parse_line()
(including the primary regexp) from Joerk Behrends <jbehrends@multimediaproduzenten.de>.
Examples section another documentation provided by John Heidemann <johnh@ISI.EDU>
Bug reports, patches, and nagging provided by lots of folks-- thanks everybody! Special thanks to Michael Schwern <schwern@envirolink.org>
for assuring me that a &nested_quotewords() would be useful, and to Jeff Friedl <jfriedl@yahoo-inc.com> for telling me not to worry about
error-checking (sort of-- you had to be there).
perl v5.14.2 2010-12-30 Text::ParseWords(3perl)