If you are using the mail command line tool, this error “Cannot append message: Conflict with previous locker” can occur if a mbox.lock file is already here in your home directory. If you quit the mail program, make sure there is no more mbox.lock file by possibly deleting it.

Should you have the following error : “Puppet(err) : Could not retrieve catalog from remote server: Could not intern from pson:unexpected token in object at ”, the following steps helped me solving this problem :

On the Puppet master :

root@puppet_master:~# puppet node clean FQDN_node

On the host (represented here as FQDN_node) running Puppet agent :

root@puppet_agent:~# find /var/lib/puppet/ssl -type f -iname '*.pem' -exec rm -rf {} \;
root@puppet_agent:~# puppet agent -t --waitforcert=60 --server=FQDN_puppet_master

Should you have the following error : “Puppet(err) : Could not retrieve catalog from remote server. Error 400 on SERVER:could not parse YAML data for node”, the following steps helped me solving this problem :

On the Puppet master :

root@puppetmaster:~# rm /var/lib/puppet/yaml/node/FQDN_node
root@puppetmaster:~# rm /var/lib/puppet/yaml/facts/FQDN_node

On the host (represented here as FQDN_node) running Puppet agent :

root@puppet_agent:~# service puppet stop
root@puppet_agent:~# puppet agent --test --server FQDN_puppet_master

If you find yourself with Bluetooth blocked or disabled, use the rfkill command to reset the Bluetooth fonctionality.
rfkill package must be installed on your system to run the following commands below :

rfkill list
0: hp-wifi: Wireless LAN
Soft blocked: yes
Hard blocked: no
1: hp-bluetooth: Bluetooth
Soft blocked: yes
Hard blocked: no
2: phy0: Wireless LAN
Soft blocked: yes
Hard blocked: no

rfkill unblock 1

rfkill list
0: hp-wifi: Wireless LAN
Soft blocked: no
Hard blocked: no
1: hp-bluetooth: Bluetooth
Soft blocked: no
Hard blocked: no
2: phy0: Wireless LAN
Soft blocked: yes
Hard blocked: no
3: hci0: Bluetooth
Soft blocked: yes
Hard blocked: no

As a precaution, restart the Bluetooth service as follows :

service bluetooth restart
[ ok ] Stopping bluetooth: rfcomm /usr/sbin/bluetoothd.
[ ok ] Starting bluetooth: bluetoothd rfcomm.

Thanks for this tip here: Cannot enable Bluetooth anymore

Here is a very interesting article about monitoring battery capacity with Debian :

Different ways to monitor battery capacity with Debian

More information about IBAM, the Intelligent Battery Monitor

Gnome-file-share-properties is a simple GUI application to let you receive or send files to a Bluetooth enabled device. It helps you enabling an  ObexFTP share.

Use /usr/bin/gnome-file-share-properties which is part of the gnome-user-share package.

In previous versions of GNOME, the program gnome-file-properties was to be used instead.

To install a working Perl environment to manage remote Oracle databases, you need to install the Oracle Instant Client

To install the Oracle Instant Client version 11.2.3.0 64 bits, download the rpm files as shown below :

root@localhost:~# rpm -i oracle-instantclient11.2-basic-11.2.0.3.0-1.x86_64.rpm
root@localhost:~#rpm -i oracle-instantclient11.2-odbc-11.2.0.3.0-1.x86_64.rpm
root@localhost:~#rpm -i oracle-instantclient11.2-sqlplus-11.2.0.3.0-1.x86_64.rpm
root@localhost:~#rpm -i oracle-instantclient11.2-devel-11.2.0.3.0-1.x86_64.rpm

The installation works fine.

To install DBD::Oracle perl module, use CPAN if it is not available from RHEL yum repositories.

root@localhost:~#cpan

cpan[1]> install DBD::Oracle

This command will install the module and the missing dependencies. if the development files of the Oracle Instant Client are not installed (oracle-instantclient11.2-devel-11.2.0.3.0-1.x86_64.rpm not installed), you will have the following error during DBD::Oracle perl compilation :

Unable to locate an oracle.mk or other suitable *.mk
file in your Oracle installation.  (I looked in
/usr/lib/oracle/11.2/client64/rdbms/demo/demo_xe.mk /usr/lib/oracle/11.2/client64/rdbms/lib/oracle.mk /usr/lib/oracle/11.2/client64/rdbms/demo/oracle.mk /usr/lib/oracle/11.2/client64/rdbms/demo/demo_rdbms.mk /usr/lib/oracle/11.2/client64/rdbms/demo/demo_rdbms64.mk /usr/lib/oracle/11.2/client64/rdbms/lib/ins_rdbms.mk /usr/share/oracle/11.2/client64/demo.mk under /usr/lib/oracle/11.2/client64)

The oracle.mk (or demo_rdbms.mk) file is part of the Oracle
RDBMS product.  You need to build DBD::Oracle on a
system which has one of these Oracle components installed.
(Other *.mk files such as the env_*.mk files will not work.)
Alternatively you can use Oracle Instant Client.

In the unlikely event that a suitable *.mk file is installed
somewhere non-standard you can specify where it is using the -m option:
perl Makefile.PL -m /path/to/your.mk

See the appropriate README file for your OS for more information and some alternatives.

at Makefile.PL line 1187.


Just a quick tip to avoid using the Esc key while leaving the insert mode in Vim.
This can be replaced with your own shortcut.
Put this within your own Vim configuration file vimrc :

inoremap jj <ESC>


or

inoremap jk<ESC>

 

hpacucli both provides monitoring and management features. It is HP proprietary tool which can help get technical information about this hardware RAID array.

List all controllers :

root@localhost:~#hpacucli controller all show
Smart Array P410i in Slot 0 (Embedded)

List arrays on controller in slot 0:

root@localhost:~#hpacucli ctrl slot=0 logicaldrive all show status
logicaldrive 1 (136.7 GB, RAID 1): OK

List physical drives on controller in slot 0:

root@localhost:~#hpacucli ctrl slot=0 pd all show status
physicaldrive 1I:1:1 (port 1I:box 1:bay 1, 146 GB): OK
physicaldrive 1I:1:2 (port 1I:box 1:bay 2, 146 GB): OK

More information about managing HP SmartArray RAID controllers under Linux :

complete documentation about managing SmartArray under Linux
hwraid GitHub website
hp-smartarray-raid-controllers-linux-driver-differences-cciss-versus-hpsa 
Debian wiki page on managing RAID

To make a Perl script portable is to avoid using system commands as much as possible. To deal with date formats actions, you’d better use DateTime or Date::Calc modules.

For a simple formatting of the current date using localtime() Perl function :

#!/usr/bin/perl
use POSIX qw(strftime);
my $date = strftime “%d-%m-%y”, localtime;

Instead of :

my $date = qx(date +%d-%m-%y);

Both work. The first one is more Perlish ;-)

More info :
POSIX Function strftime() in Perl
DateTime Perl module
Date::Calc Perl module