A file handle is an abstract indicator for accessing a file. It is retrieved after successfully opening the file using the file name. Afterwards the file handle is used instead of the file name for all file operations.
Questions tagged [filehandle]
388 questions
14
votes
1 answer
I can create filehandles to strings in Perl 5, how do I do it in Perl 6?
In Perl 5, I can create a filehandle to a string and read or write from the string as if it were a file. This is great for working with tests or templates.
For example:
use v5.10; use strict; use warnings;
my $text = "A\nB\nC\n";
open(my $fh, '<',…
Christopher Bottoms
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14
votes
2 answers
Prevent strings from being interpreted as a file handle
Perl has the feature that strings named like a file handle are taken to be a filehandle:
# let this be some nice class I wrote
package Input {
sub awesome { ... }
}
So when we do Input->awesome or extra-careful: 'Input'->awesome, the method…
amon
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13
votes
2 answers
Close all open files in ipython
Sometimes when using ipython you might hit an exception in a function which has opened a file in write mode. This means that the next time you run the function you get a value error,
ValueError: The file 'filename' is already opened. Please close…
tdc
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13
votes
1 answer
How do I determine whether a Perl file handle is a read or write handle?
You are given either an IO::File object or a typeglob (\*STDOUT or Symbol::symbol_to_ref("main::FH")); how would you go about determining if it is a read or write handle? The interface cannot be extended to pass this information (I am overriding…
Chas. Owens
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12
votes
5 answers
How can I test if I can write to a filehandle?
I have some subroutines that I call like this myWrite($fileName, \@data). myWrite() opens the file and writes out the data in some way. I want to modify myWrite so that I can call it as above or with a filehandle as the first argument. (The main…
flies
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12
votes
5 answers
Is there a way to access a string as a filehandle in php?
I'm on a server where I'm limited to PHP 5.2.6 which means str_getcsv is not available to me. I'm using, instead fgetcsv which requires "A valid file pointer to a file successfully opened by fopen(), popen(), or fsockopen()." to operate on.
My…
Erik
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11
votes
5 answers
Python equivalent of piping file output to gzip in Perl using a pipe
I need to figure out how to write file output to a compressed file in Python, similar to the two-liner below:
open ZIPPED, "| gzip -c > zipped.gz";
print ZIPPED "Hello world\n";
In Perl, this uses Unix gzip to compress whatever you print to the…
bu11d0zer
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11
votes
5 answers
Why does Programming Perl use local (not my) for filehandles?
When I read through Programming Perl, 2nd Edition, Page 51, something confuses me :
sub newopen {
my $path = shift;
local *FH; #not my!
open (FH, $path) || return undef;
return *FH;
}
$fh = newopen('/etc/passwd');
My I know, why…
Cheok Yan Cheng
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2 answers
How do I release file system locks after cloning repo via JGit
I am playing around with cloning a remote existing repo with jGit following the guide here:
https://github.com/centic9/jgit-cookbook/blob/master/src/main/java/org/dstadler/jgit/porcelain/CloneRemoteRepository.java
I'm using CFML for my example:
Git…
Brad Wood
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10
votes
4 answers
Sending data to a program via stdin and ostream. (C++)
I would like to send data from within my C++ program to an external pipeline, like so:
FILE* file = popen("my_prog -opt | other_prog", "w");
std::ostream fileStream = some_function(file);
fileStream << "some data";
I understand there is no simple,…
Drew
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9
votes
3 answers
What is the difference between writing to STDOUT and a filehandle opened to "/dev/tty"?
What are the differences between this two examples?
#!/usr/bin/perl
use warnings;
use 5.012;
my $str = "\x{263a}";
open my $tty, '>:encoding(utf8)', '/dev/tty' or die $!;
say $tty $str;
close $tty;
open $tty, '>:bytes', '/dev/tty' or die $!;
say…
sid_com
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8
votes
3 answers
Can I use Text::CSV_XS to parse a csv-format string without writing it to disk?
I am getting a "csv file" from a vendor (using their API), but what they do is just spew the whole thing into their response. It wouldn't be a significant problem except that, of course, some of those pesky humans entered the data and put in…
Paul R N
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8
votes
2 answers
Why does Perl open() documentation use two different FILEHANDLE styles?
The documentation for the open function shows the syntax of open() as:
open FILEHANDLE,EXPR
open FILEHANDLE,MODE,EXPR
open FILEHANDLE,MODE,EXPR,LIST
open FILEHANDLE,MODE,REFERENCE
open FILEHANDLE
Down in the examples they have places where a…
Scooter
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8
votes
7 answers
How can I process a multi line string one line at a time in perl with use strict in place?
I'm trying to figure out the proper PBP approved way to process a multi line string one line at a time. Many Perl coders suggest treating the multi line string as a filehandle, which works fine unless you have "use strict" in your script. Then you…
Kurt W. Leucht
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8
votes
1 answer
Support autovivified filehandle as arguments to Perl XS routine
Question
How can I support autovivified filehandle arguments in an XS function?
I'm XS-wrapping a C function which returns a file descriptor, and I'd like to present that file descriptor as a perl filehandle argument in the manner of open(). …
pilcrow
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