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Full Discussion: help me in file reading
Top Forums Shell Programming and Scripting help me in file reading Post 302147429 by vino on Tuesday 27th of November 2007 02:40:24 AM
Old 11-27-2007
Quote:
Originally Posted by useless79
hi ,

could any one tell me why i m not getting the value of variable i outside the
while loop in file reading

cat filename | while read line
do
i=2
done

echo $i

here it is not showing the value of i . what i have to do if i want to persist the value of
i outside the while loop
thanks
In this case, the pipe spawns a sub-shell and assigns i=2. When it comes out of the subshell, it does retain the value of i. Think scoping and you will understand.

Do this and you will get what you are looking for

Code:
while read line
do
  i=2
done < filename
echo $i


Last edited by vino; 11-27-2007 at 05:34 AM.. Reason: minor correction.
 

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IO::Async::Timer::Absolute(3pm) 			User Contributed Perl Documentation			   IO::Async::Timer::Absolute(3pm)

NAME
"IO::Async::Timer::Absolute" - event callback at a fixed future time SYNOPSIS
use IO::Async::Timer::Absolute; use POSIX qw( mktime ); use IO::Async::Loop; my $loop = IO::Async::Loop->new; my @time = gmtime; my $timer = IO::Async::Timer::Absolute->new( time => mktime( 0, 0, 0, $time[4]+1, $time[5], $time[6] ), on_expire => sub { print "It's midnight "; $loop->stop; }, ); $loop->add( $timer ); $loop->run; DESCRIPTION
This subclass of IO::Async::Timer implements one-shot events at a fixed time in the future. The object waits for a given timestamp, and invokes its callback at that point in the future. For a "Timer" object that waits for a delay relative to the time it is started, see instead IO::Async::Timer::Countdown. EVENTS
The following events are invoked, either using subclass methods or CODE references in parameters: on_expire Invoked when the timer expires. PARAMETERS
The following named parameters may be passed to "new" or "configure": on_expire => CODE CODE reference for the "on_expire" event. time => NUM The epoch time at which the timer will expire. Once constructed, the timer object will need to be added to the "Loop" before it will work. Unlike other timers, it does not make sense to "start" this object, because its expiry time is absolute, and not relative to the time it is started. AUTHOR
Paul Evans <leonerd@leonerd.org.uk> perl v5.14.2 2012-10-24 IO::Async::Timer::Absolute(3pm)
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