PERL: reading Log file and cmd line input together - perl

Question

I have written a script which is reading some data from log file and transform the data to simpler form and writing it back to another file. the reading is done line by line with a delay of 5 seconds i.e. sleep(5).
Meanwhile, on the command line if a user enters 'suspend' (through STDIN) then the program went on to sleep unless 'resume' is not entered and then read the next line.
Since, with every iteration in the loop I am checking STDIN whether 'suspend' is entered or not by the user.
if not then read the next line from the file. but when my programs runs I have to at least hit a ENTER key, otherwise it does not picks the next line from the input log file albeit i put an if statement to check if STDIN is undefined or not.
I am not a perl expert and this the first time I am writing a code in PERL. infact i have never done this file parsing thing before :'-(
my code implementation is like this;
#!/usr/local/bin/perl
my $line_no = 0;my $cancel = 0; my $line = "";
my $curpos = 0; my $whence = 0;
my $log_file = "/var/log/tmp_nagios.log";
#open(LOGFILE, "+< $log_file")or die "Failed to open $log_file, $!";
my $inp_file = "/var/log/sec_input";
my $logbuffer="";
#open(LOGFILE, "+< $log_file")or die "Failed to open $log_file, $!";
my $in;
while(1){
print "in While (1) Pos: $curpos and Whence:$whence\n";
open(LOGFILE, "+< $log_file")or die "Failed to open $log_file, $!";
seek(LOGFILE, $curpos, $whence);
next if(eof(LOGFILE));
print "Beginning\n";
while(<LOGFILE>){
#chomp($in = <STDIN>);
#if(defined($in) && $in =~ /^suspend$/i){
### Problem here ###
if(defined(<STDIN>) && <STDIN> =~ /^suspend\n$/i){ ## checking if 'suspend' is entered
print "Suspend Mode";
do{
sleep(5);
}while(!(<STDIN> =~ /^resume\n$/i));
print "Resume now\n";
close(LOGFILE);
last;
}
else{
$line = $_;
if($line =~ m/^\[(\d+)\]\sCURRENT\sSERVICE\sSTATE:\s(\w+);(\w+|\_|\d+)+;(CRITICAL|OK);.+$/){
$logbuffer = "$1,$2-$3,$4\n";
print $logbuffer;
open(INPFILE, ">> $inp_file")or die "Failed! to open $inp_file, $!";
#print INPFILE $logbuffer;
close(INPUTFILE);
sleep(5);
$curpos = tell(LOGFILE);
$whence = 1;
}
}
}
print "\nRe openning the file from Pos=$curpos and Whence=$whence\n";
}
close(LOGFILE);
here is the sample log file (/var/log/tmp_nagios.log) data;
[1284336000] CURRENT SERVICE STATE: host1;event1;CRITICAL; s
[1284336000] CURRENT SERVICE STATE: host2;event1;CRITICAL; f
[1284336000] CURRENT SERVICE STATE: host3;event3;CRITICAL; g
[1284336000] CURRENT SERVICE STATE: host4;event4;CRITICAL; j
[1284336000] CURRENT SERVICE STATE: host5;event1;CRITICAL; s
[1284336000] CURRENT SERVICE STATE: host6;event1;CRITICAL; f
[1284336000] CURRENT SERVICE STATE: host7;event7;CRITICAL; s
Sorry guys! Typo mistake
In the beginning I said, 'my script is reading data from log file with a delay of 5 seconds i.e. sleep(5)'
but actually i forget to mention it in my code, therefore, uncomment this line: #sleep(3); and make 'sleep(5);'
thanks

Answer 1

If I have understood your question correctly: check out the Term::ReadKey CPAN Module.
You can use it to do non-blocking buffer reads. (If there is nothing in the buffer, your script does not pause for user input)
https://metacpan.org/pod/Term::ReadKey
You may also like to approach this problem slightly differently - using signals:
http://perldoc.perl.org/perlipc.html. You can have your program run normally, but capture interrupts (e.g. CTRL-C)
Alternatively, you could just use CTRL-Z and fg to make your script sleep and wake.

Answer 2

Another option is POE::Wheel::FollowTail for the log and POE::Wheel::ReadLine or Term::Visual for user input. Though this might be a little overkill