One of the senior administrators gave me a shell script to modify and it begins as follows:
if ] && ]
{more code follows}
Why the double square brackets? (10 Replies)
Hi
First apologies if this has been raised before.
I've got the following in a ksh script:
if ]
For some reason this does not work. But if I remove the double square brackets to:
if
This works.
I thought ksh supported the ]. Or is there more to it?
Thanks in advance. (3 Replies)
Hi,
I just came across an interesting shell script syntax like the one below:
] && (trap 'rm -rf ${WORK_DIR}/*.$$; echo "\n\nInterrupted !!\n\n"; exit 4' 1 2 3 15)
Can someone please explain the code snippet above?
The trap command bit is fine but ] && is the hazy part.
Generally we use an... (2 Replies)
Hello,
Can someone please explain to me the following line,
] && break
I do not understand why two test square brackets are used.
Thanks,
Shantanu
---------- Post updated at 03:38 PM ---------- Previous update was at 03:35 PM ----------
And, also why there's a $ before (echo $c |... (5 Replies)
Hi All,
I have a text file which looks like this:
computer programming
systems engineering
I want to get rid of these square brackets and also the text that is inside these brackets. So that my final text file looks like this:
computer programming
systems engineering
I am using... (3 Replies)
Hi frieds, I don't understand the difference between single square bracket and double square brackets in a IF condition.
Ex.
if ;
then
RETURNJOB=1
else
RETURNJOB=0
fi
It run, but this
if ];
then
RETURNJOB=1
else
RETURNJOB=0
fi (4 Replies)
I wanted to compare the value inside the Squre bracket after Colon ( : ) based on any value(seperated by or operator | ) inside the variable Thread and if match found then wnated to store in output file
Input file :
20140320 00:08:43.918 INO 35] - Corporate hub is
20140320 00:08:43.918... (2 Replies)
Hello all,
I have the following problem:
$ cat infile
this is spam and i need this too
this is spam and i need this too
$ perl -nwe '$_ =~ /]+ \]+)\]\]*\]? (\+)$/; print "$1 - $2\n";' infile
i need this - too
i need this - and i need this too
I am not sure how many occurences of... (13 Replies)
Hi All,
Hope you all are doing good. Yesterday in my project i came across a scenario which i can not guess why it was working in one region and why it was not in another region. Please find my issue below.
I am using AIX version 6.0 of UNIX in my project, in shell scripting i have the... (1 Reply)
Discussion started by: mad man
1 Replies
LEARN ABOUT DEBIAN
poe::filter::grep
POE::Filter::Grep(3pm) User Contributed Perl Documentation POE::Filter::Grep(3pm)NAME
POE::Filter::Grep - select or remove items based on simple rules
SYNOPSIS
#!perl
use POE qw(
Wheel::FollowTail
Filter::Line Filter::Grep Filter::Stackable
);
POE::Session->create(
inline_states => {
_start => sub {
my $parse_input_as_lines = POE::Filter::Line->new();
my $select_sudo_log_lines = POE::Filter::Grep->new(
Put => sub { 1 },
Get => sub {
my $input = shift;
return $input =~ /sudo[d+]/i;
},
);
my $filter_stack = POE::Filter::Stackable->new(
Filters => [
$parse_input_as_lines, # first on get, last on put
$select_sudo_log_lines, # first on put, last on get
]
);
$_[HEAP]{tailor} = POE::Wheel::FollowTail->new(
Filename => "/var/log/system.log",
InputEvent => "got_log_line",
Filter => $filter_stack,
);
},
got_log_line => sub {
print "Log: $_[ARG0]
";
}
}
);
POE::Kernel->run();
exit;
DESCRIPTION
POE::Filter::Grep selects or removes items based on simple tests. It may be used to filter input, output, or both. This filter is named
and modeled after Perl's built-in grep() function.
POE::Filter::Grep is designed to be combined with other filters through POE::Filter::Stackable. In the "SYNOPSIS" example, a filter stack
is created to parse logs as lines and remove all entries that don't pertain to a sudo process. (Or if your glass is half full, the stack
only selects entries that DO mention sudo.)
PUBLIC FILTER METHODS
In addition to the usual POE::Filter methods, POE::Filter::Grep also supports the following.
new
new() constructs a new POE::Filter::Grep object. It must either be called with a single Code parameter, or both a Put and a Get parameter.
The values for Code, Put, and Get are code references that, when invoked, return true to select an item or false to reject it. A Code
function will be used for both input and output, while Get and Put functions allow input and output to be filtered in different ways. The
item in question will be passed as the function's sole parameter.
sub reject_bidoofs {
my $pokemon = shift;
return 1 if $pokemon ne "bidoof";
return;
}
my $gotta_catch_nearly_all = POE::Filter::Grep->new(
Code => &reject_bidoofs,
);
Enforce read-only behavior:
my $read_only = POE::Filter::Grep->new(
Get => sub { 1 },
Put => sub { 0 },
);
modify
modify() changes a POE::Filter::Grep object's behavior at run-time. It accepts the same parameters as new(), and it replaces the existing
tests with new ones.
# Don't give away our Dialgas.
$gotta_catch_nearly_all->modify(
Get => sub { 1 },
Put => sub { return shift() ne "dialga" },
);
SEE ALSO
POE::Filter for more information about filters in general.
POE::Filter::Stackable for more details on stacking filters.
BUGS
None known.
AUTHORS & COPYRIGHTS
The Grep filter was contributed by Dieter Pearcey. Documentation is provided by Rocco Caputo.
Please see the POE manpage for more information about authors and contributors.
perl v5.14.2 2012-05-15 POE::Filter::Grep(3pm)