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Top Forums UNIX for Dummies Questions & Answers Perl find & replace - what am I doing wrong? Post 302814617 by sudon't on Wednesday 29th of May 2013 09:00:23 PM
Old 05-29-2013
Quote:
To be honest, I dislike perl
Yes, you have mentioned this to me. ; ) Now, obviously you know more about it than I do, but in my defense let me just say that the little find/replace thing I learned, (or thought I had), appears simple to me:
Code:
perl -pi -e 's/read/write/g' /path/to/file

Much of the reason is that I see "one-liners" as quick and easy. And part of the reason is that it "works in place" rather than creating new files. Also, I like the notion of a perl pie!
But ok, I read your post on the -i flag. I'm not sure how much of that would come into play for me. After all, I'm a truck driver, not a sysadmin, and just playing on my personal computer. But I do understand and appreciate developing good practices, and you are correct to encourage that.
Ok, here are my questions:
How is the line being deleted? Is that what the d operator is saying, delete? And will it then delete any line which contains the preceding string? In other words, if we know that only our target line contains "PhotoBooth", would that be enough to get rid of the whole line?
Code:
'/PhotoBooth/d'

Why do certain characters have to be escaped? I thought if the regex is quoted, it's protected from the shell.
 

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IO::Async::Protocol::LineStream(3pm)			User Contributed Perl Documentation		      IO::Async::Protocol::LineStream(3pm)

NAME
"IO::Async::Protocol::LineStream" - stream-based protocols using lines of text SYNOPSIS
Most likely this class will be subclassed to implement a particular network protocol. package Net::Async::HelloWorld; use strict; use warnings; use base qw( IO::Async::Protocol::LineStream ); sub on_read_line { my $self = shift; my ( $line ) = @_; if( $line =~ m/^HELLO (.*)/ ) { my $name = $1; $self->invoke_event( on_hello => $name ); } } sub send_hello { my $self = shift; my ( $name ) = @_; $self->write_line( "HELLO $name" ); } This small example elides such details as error handling, which a real protocol implementation would be likely to contain. DESCRIPTION
EVENTS
The following events are invoked, either using subclass methods or CODE references in parameters: on_read_line $line Invoked when a new complete line of input is received. PARAMETERS
The following named parameters may be passed to "new" or "configure": on_read_line => CODE CODE reference for the "on_read_line" event. METHODS
$lineprotocol->write_line( $text ) Writes a line of text to the transport stream. The text will have the end-of-line marker appended to it; $text should not end with it. AUTHOR
Paul Evans <leonerd@leonerd.org.uk> perl v5.14.2 2012-10-24 IO::Async::Protocol::LineStream(3pm)
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