Firewall Commands on CentOS 7

Open a firewall port

   30  firewall-cmd --zone=public --add-port=4407/tcp --permanent
   31  firewall-cmd --reload

Show opened ports

  568  firewall-cmd --zone=public --list-ports

List connected servies

  567  firewall-cmd --zone=public --list-services

Find out whether an NIC is connected and has link

root@host ~
$ ip link show dev eth0
3: eth0:  mtu 1500 qdisc pfifo_fast master bond0 state UP qlen 1000
    link/ether 00:xx:xx:xx:xx:ef brd ff:ff:ff:ff:ff:ff
root@host ~
$ ip link show dev eth1
2: eth1:  mtu 1500 qdisc pfifo_fast master bond1 state DOWN qlen 1000
    link/ether 00:xx:xx:xx:xx:ed brd ff:ff:ff:ff:ff:ff
root@nost ~

If NetworkManager is installed but not used facter throws a warning - Puppet

The solution for this is simple!

yum remove NetworkManager

When a process shows uid number instead of user name

When a process appears with the uid number instead of the username, it is because the username is more than 8 characters long:

[root@ pe-activemq]# ps -ef|grep active
497       2578     1  0 12:44 ?        00:00:27 /opt/puppet/lib/jvm/pe-java/jre/bin/java -Xms512m -Xmx512m -Djava.util.logging.config.file=logging.properties -Dhawtio.realm=activemq -Dhawtio.role=admins -Dhawtio.rolePrincipalClasses=org.apache.activemq.jaas.GroupPrincipal -Djava.security.auth.login.config=/etc/puppetlabs/activemq/login.config -Dcom.sun.management.jmxremote -Djava.awt.headless=true -Djava.io.tmpdir=/opt/puppet/share/activemq/tmp -Dactivemq.classpath=/etc/puppetlabs/activemq; -Dactivemq.home=/opt/puppet/share/activemq -Dactivemq.base=/opt/puppet/share/activemq -Dactivemq.conf=/etc/puppetlabs/activemq -Dactivemq.data=/opt/puppet/share/activemq/data -jar /opt/puppet/share/activemq/bin/activemq.jar start
root     16591  7586  0 13:30 pts/0    00:00:00 grep active

Use the command option -o to shown fullname:

[root@ pe-activemq]# ps -e -o "user:16,pid,ppid,c,stime,tty,time,command"|grep active
pe-activemq       2578     1  0 12:44 ?        00:00:28 /opt/puppet/lib/jvm/pe-java/jre/bin/java -Xms512m -Xmx512m -Djava.util.logging.config.file=logging.properties -Dhawtio.realm=activemq -Dhawtio.role=admins -Dhawtio.rolePrincipalClasses=org.apache.activemq.jaas.GroupPrincipal -Djava.security.auth.login.config=/etc/puppetlabs/activemq/login.config -Dcom.sun.management.jmxremote -Djava.awt.headless=true -Djava.io.tmpdir=/opt/puppet/share/activemq/tmp -Dactivemq.classpath=/etc/puppetlabs/activemq; -Dactivemq.home=/opt/puppet/share/activemq -Dactivemq.base=/opt/puppet/share/activemq -Dactivemq.conf=/etc/puppetlabs/activemq -Dactivemq.data=/opt/puppet/share/activemq/data -jar /opt/puppet/share/activemq/bin/activemq.jar start
root             17623  7586  0 13:37 pts/0    00:00:00 grep active
root             17391 grep active

Add CDROM as local yum repo - CentOS 7

Mount the CD/DVD ROM on the any directory of your wish, for testing mount it on /cdrom.

# mkdir /cdrom
# mount /dev/cdrom /cdrom

Configuration file: Create the new repo file called cdrom.repo under /etc/yum.repos.d directory. # vi /etc/yum.repos.d/local.repo Add the following details.

[LocalRepo]
name=Local Repository
baseurl=file:///cdrom
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

Regenerate authorized_keys file in GitLab

sudo gitlab-rake gitlab:shell:setup

To check your GitLab for issues:

sudo gitlab-rake gitlab:check RAILS_ENV=production

Disk Usage - What's eating my disk space Perl script

#!/usr/bin/perl
use strict;
use IO::File;

my $size;
my $inode;
my $sum = 0;
my @entries;
my $e;
my $percent = 0;
my $remsum = 0;
my $counter = 0;
my $nofiles = 0;

my $du = new IO::File;

if (@ARGV) {
    chdir "$ARGV[0]" or die "cannot change to [ $ARGV[0] ]\n";
}

my $path =  $ARGV[0] . "/";
print "$path\n";
START:

$du->open("du -sk *|") or
    die "cannot open du program and pipe";

while (<$du>) {
    ($size, $inode)=split;
    $inode .= "/" if (-d $inode);
    $sum += $size;
    push @entries, { size => $size, inode => $inode };
}

@entries = sort { $b->{size} <=> $a->{size} } @entries;

$du->close;

foreach $e (@entries) {
    $percent = $e->{size}/$sum*100;

    if ($counter < 10) {
        printf(
            "%30s | %5d | %5.2f%%\n",
            $e->{inode},
            $e->{size},
            $percent);
    }
    else {
        $nofiles++;
        $remsum += $e->{size};
    }
    $counter++;
}

if ($remsum > 0) {
    printf(
        "%30s | %5d | %5.2f%%\n",
        "files",
        $remsum,
        $remsum/$sum*100);
}


if (@entries[0]->{inode} =~ /(.*\/$)/)
{
    $path .= $1;
    chdir $path;
    print "$path\n";
    undef @entries;
    $counter=0; $nofiles=0;
    goto START;
}
else
{
    print "No more!";
    exit;
}