Perl regex matching output from `w -hs` command
- by Bushman
I'm trying to write a Perl script that will work better with KDE's kwrited, which, as far as I can tell, is connected to a pts and puts every line it receives through the KDE system tray notifications, with the title "KDE write daemon". Unfortunately, it makes a separate notification for each and every line, so it spams up the system tray with multiline messages on regular old write, and for some reason it cuts off the entire last line of the message when using wall (One-line messages are also goners.). I was also hoping to make it so that it could broadcast across a LAN with thick clients. Before starting on that (which would require ssh, of course), I tried to make an ssh-less version to make sure it works. Unfortunately, it doesn't. perl ./write.pl "Testing 1 2 3" where the following is the contents of ./write.pl:
#!/usr/bin/perl
use strict;
use warnings;
my $message = "";
my $device = "";
my $possibledevice = '`w -hs | grep "/usr/bin/kwrited"`'; #Where is kwrited?
$possibledevice =~ s/^[^\t][\t]//;
$possibledevice =~ s/[\t][^\t][\t ]\/usr\/bin\/kwrited$//;
$possibledevice = '/dev/'.$possibledevice;
unless ($possibledevice eq "") {
$device = $possibledevice;
}
if ($ARGV[0] ne "") {
$message = $ARGV[0];
$device = $ARGV[1];
}
else {
$device = $ARGV[0] unless $ARGV[0] eq "";
while (<STDIN>) {
chomp;
$message .= <STDIN>;
}
}
if ($message ne "") {
system "echo \'$message\' > $device";
}
else {
print "Error: empty message"
}
produces the following error:
$ perl write.pl "Testing 1 2 3"
Use of uninitialized value $device in concatenation (.) or string at write.pl line 29.
sh: -c: line 0: syntax error near unexpected token `newline'
sh: -c: line 0: `echo 'foo' > '
Somehow, the regular expressions and/or the backtick escape in processing $possibledevice are not working properly, because where kwrited is connected to /dev/pts/0, the following works perfectly:
$ perl write.pl "Testing 1 2 3" /dev/pts/0
