Re^2: system commands/shell and perl variables.

Hi there, First of all thank you very much. I am starting with perl and I trying to automate my shell scripts by perl scripts. Here my final script ( of course I will follow HAUKEX advice which is what I want.


#!/usr/local/bin/perl
use strict;
use warnings;

my @get_vmlist = ( `xl list` );

sub show_vmlist {
        print @get_vmlist;
}


my $arg =  shift @ARGV;
my $vm_run = pop @ARGV;

sub get_vncport {
        my $DOMID = qq(DOM_ID="`xl list | fgrep $vm_run | awk '{print 
+\$2}'`" && VNCPORT="`ps x | fgrep -m 1 "domid \$DOM_ID" | awk '{print
+ \$1}'`" && sockstat -4l | fgrep \$VNCPORT | awk '{print \$6}');
        print `$DOMID`;
}

my %rec_args = ( vmlist => \&show_vmlist,
        getvnc => \&get_vncport,
);

if (defined $arg && exists $rec_args{$arg}) {
        $rec_args{$arg}->();
}
[download]

Comment on Re^2: system commands/shell and perl variables. Download Code

Replies are listed 'Best First'.
Re^3: system commands/shell and perl variables. by haukex (Archbishop) on Jan 22, 2019 at 18:00 UTC
Since I don't have that program, could you perhaps show the output of a typical `xl list` command, and show and explain the expected output for that input (both in `<code>` tags)? See also How do I post a question effectively? and Short, Self-Contained, Correct Example. Also note the Basic debugging checklist, where it is mentioned that you can and should use a module such as Data::Dumper to show what your variables contain.	[reply] [d/l] [select]
Re^4: system commands/shell and perl variables. by knight.neo (Initiate) on Jan 22, 2019 at 19:07 UTC
Hi haukex, Absolutely , xl is part of xen-tools. xl is used to manipulate virtual machines as other system parameters as well. Here is a tipical output of "xl list" ( used to list running virtual machines ) I am using FreeBSD as dom0. When I start a VM on HVM mode, I use VNC to access vm console. `# xl list Name ID Mem VCPUs State + Time(s) Domain-0 0 18442 2 r----- + 16256.2 git 1 1023 2 -b---- + 14499.4 zabbix 2 512 1 -b---- + 3228.6 jenkins 3 4096 2 -b---- + 21733.3 openbsd 4 2048 1 -b---- + 1202.6 wiki 5 2048 1 -b---- + 1140.4 builder 6 4096 2 -b---- + 206.9` [download] This perl script which you guys helped, do the follow: "pxl vmlist" ( which will return xl list ), and "pxl getvnc jenkins" ( which will return vnc port listening of that VM ) "127.0.0.1:5906" Next steps, I will provide ssh port forward and connect to it :) Thanks again	[reply] [d/l]
Re^5: system commands/shell and perl variables. by haukex (Archbishop) on Jan 23, 2019 at 20:15 UTC
Since I don't have all the commands you're using on my system, here are just some general tips. Your `command \| fgrep \| awk` sequences can be rewritten in Perl in the following manner, using `xl list` as an example. You can write these loops one after the other, first getting the ID, then the VNC port, and finally for the IP address. `use warnings; use strict; use IPC::System::Simple qw/capturex/; my $vm_run = 'zabbix'; my $id; for ( capturex('xl','list') ) { # loop over lines of command output chomp; # remove newline my @F = split; # split the line into fields on whitespace (like a +wk) if ( $F[0] eq $vm_run ) { # match on the first field $id = $F[1]; # store the second field #last; # would be the equivalent of fgrep -m1 } } print "ID: $id\n"; # prints "ID: 2" in this example` [download] Also, I suspect print `$DOMID`; isn't right, you probably don't want to execute the contents of the `$DOMID` as a command (that's what the backticks will do)? You probably want a simple `print "$DOMID\n";` instead.	[reply] [d/l] [select]