Short Notes on Linux Administration
Reset Compiz to Default Settings
gconftool-2 --recursive-unset /apps/compiz
Enable and Start sendmail
If you're getting "stat=Deferred: Connection refused by [127.0.0.1]" log messages from sendmail, try adding the following line to your /etc/mail/sendmail.mc file:
DAEMON_OPTIONS(`Port=smtp, Addr=127.0.0.1, Name=MTA')
under the "General defines" section.
Also, make sure the sendmail daemon is running:
ps aux | grep sendmail
If not, run it using
sendmail -bd -q1m
where -q parameter chooses how often the email queue's new messages should be processed (here, every minute).
To test if this all works, use
echo -e "Subject: Hello\nTesting the mailer..." | sendmail -f firstname.lastname@example.org email@example.com
The advantage of sendmail over mail is that the from address need not be a valid email address... well... advantage?
On most systems, sendmail comes as a package, and typically gets started during the boot from the init.d/rc.d scripts.
If you want/need to start sendmail manually, or it has died, use
or, for debugging purposes
that will start sendmail daemon, but will keep it in foreground, so you can see its output.
Sending Emails using sendmail
The easiest way is to create the message file with all necessary definitions, e.g.
To: Mr. Recepient <firstname.lastname@example.org> Subject: This is a fine example of a subject Date: 2011-08-15 20:00:00 +0000 From: Mr. Sender <email@example.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Disposition: inline User-Agent: My email service The body of the message comes here, after a single blank line...
and then feed this file to sendmail:
sendmail -t < message_file.txt
Find and Mark Bad Blocks
To test partition /dev/sdXN (such as, /dev/sda1) for bad blocks simply run:
$ sudo backblocks -sv /dev/sdXN > ~/bad-blocks-list $ fsck -l ~/bad-blocks-list /dev/sdXN
Using TLP to Optimize Battery Lifetime
# check TLP status and system info $ sudo tlp-stat -s --- TLP 1.1 -------------------------------------------- +++ System Info [...] +++ TLP Status State = enabled Last run = 09:13:49, 403 sec(s) ago Mode = battery Power source = battery # get battery information $ sudo tlp-stat -b --- TLP 1.1 -------------------------------------------- +++ Battery Status /sys/class/power_supply/BAT0/manufacturer = CPT-COS /sys/class/power_supply/BAT0/model_name = L17C4PB0 /sys/class/power_supply/BAT0/cycle_count = (not supported) /sys/class/power_supply/BAT0/energy_full_design = 45520 [mWh] /sys/class/power_supply/BAT0/energy_full = 44540 [mWh] /sys/class/power_supply/BAT0/energy_now = 37370 [mWh] /sys/class/power_supply/BAT0/power_now = 20057 [mW] /sys/class/power_supply/BAT0/status = Discharging Charge = 83.9 [%] Capacity = 97.8 [%] # CPU temperature and fan speed $ sudo tlp-stat -t # CPU info $ sudo tlp-stat -p # warnings $ sudo tlp-stat -w