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Top Forums Shell Programming and Scripting Bash not equal string comparison Post 302920410 by RavinderSingh13 on Thursday 9th of October 2014 10:04:35 AM
Old 10-09-2014
Quote:
Originally Posted by cokedude
Why does this cause an infinite loop?

Code:
#!/bin/bash
 
 
while [[ "$(ipcs | awk '{print $2}')" != "Semaphore" ]]; do
    echo "$(ipcs | awk '{print $2}')"
 
done
 
echo 
exit 0

I have verified I eventually get Semaphore so it should break out of the while loop.

Code:
$ echo $(ipcs | awk '{print $2}')
Shared shmid 262145 294914 2326531 Semaphore semid Message msqid

Hi cokedude,
Could you please try following.

Code:
while [[ "$(ipcs | awk '{print $2}')" !~ "Semaphore" ]]; do
    echo "$(ipcs | awk '{print $2}')" 
done 
echo 
exit 0

Thanks,
R. Singh
 

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IO::Async::Signal(3pm)					User Contributed Perl Documentation				    IO::Async::Signal(3pm)

NAME
"IO::Async::Signal" - event callback on receipt of a POSIX signal SYNOPSIS
use IO::Async::Signal; use IO::Async::Loop; my $loop = IO::Async::Loop->new; my $signal = IO::Async::Signal->new( name => "HUP", on_receipt => sub { print "I caught SIGHUP "; }, ); $loop->add( $signal ); $loop->run; DESCRIPTION
This subclass of IO::Async::Notifier invokes its callback when a particular POSIX signal is received. Multiple objects can be added to a "Loop" that all watch for the same signal. The callback functions will all be invoked, in no particular order. EVENTS
The following events are invoked, either using subclass methods or CODE references in parameters: on_receipt Invoked when the signal is received. PARAMETERS
The following named parameters may be passed to "new" or "configure": name => STRING The name of the signal to watch. This should be a bare name like "TERM". Can only be given at construction time. on_receipt => CODE CODE reference for the "on_receipt" event. Once constructed, the "Signal" will need to be added to the "Loop" before it will work. AUTHOR
Paul Evans <leonerd@leonerd.org.uk> perl v5.14.2 2012-10-24 IO::Async::Signal(3pm)
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