FreeBSD - CPU code in dmesg meanings

Platform :
FreeBSD








Objective :
What are those CPU features flags means in "dmesg", e.g.

Features=0xfebfbff&ltFPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,
PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS&gt
Features2=0x82982203&ltSSE3,PCLMULQDQ,SSSE3,CX16,SSE4.1,SSE4.2,POPCNT,
AESNI,&ltb31&gt&gt
AMD Features=0x28100000&ltNX,RDTSCP,LM&gt
AMD Features2=0x1&ltLAHF&gt

Exim - How to force deliver email from exim mail queue

Platform :
FreeBSD

Mail Server :
Exim

Purpose :
Make Exim to start deliver all frozen messages.

Mysql - Error about packet too big while importing sql database

Q : While importing database in mysql, an error message pops out "ERROR 1153 (08S01) at line 232: Got a packet bigger than 'max_allowed_packet' bytes"
E.g.

$ mysql5 -u db_user -p db_table < db_table.sql 
Enter password: 
ERROR 1153 (08S01) at line 232: Got a packet bigger than 'max_allowed_packet' bytes

A : The file importing contains a statement that's probably too big, increase the value "max_allowed_packet" in my.cnf:

Subversion - Branching and merging to release, stable or something else

Previously, we talk about the basic stuff of Subversion. This is still basic stuff :p


Is about managing source codes by branching. Branching is a way to have 2 or more sets of source code with each has it's own development, but eventually, merging them into the main trunk.

Example, in most development, we normally have "development" & "release" version. As word means, the "development" version is meant for development & testing. But the "release" version, would be the ultimate version that roll out for production use. For this example, "release" will be the trunk & "development" will be the branch.

A view of it :

web_blog(repository)
   |
   +release
   |  |
   |  +front_end
   |  |
   |  +engine
   | 
   | 
   +development
      |
      +front_end
      |
      +engine

To create this hierarchy :

FreeBSD - How to check what services or port opening in tcp/udp

Platform :
FreeBSD

How to :
List/show what services or port is listening/opening.

Installation :
The command comes with base system.

bash - working with ps

Platform :
FreeBSD

Objective :
To grab the process details of a pid, without resorting to parse the output of process status command , "ps" :
E.g.

ps aux | grep -i pid

Bash - How to debug shell script

Although Bash will spit out the errors onto the screen whenever it hits one, but some times, we want to know what exactly was being done every single command it executed.

This is how to do it :
Before running the bash script, do a :

set -x

then run the script and it'll be tell every action that it performs.

This is especially useful when debugging logic.

After finding out what's wrong, this is how to turn it off :

set +x

Alternatively, to debug only when running this script, put the below line in the start of the script :

set -x

Arrivederci !!!

Perl - How to DOS your processor

Here's a way to maximize the CPU processor,

Sendmail - How to test sending email, verbosely using Sendmail

Mail Server :

Sendmail

Purpose :

To verbosely test sending of email using sendmail

Here how :

Prepare a file with name "mail.txt". This will be the email header & contents that we wanna include when test sending this email. The contents of the file should look like below :

PC-BSD - Error when restarting pf firewall or within Ports Jail

Trigger :

When pf service is restarted

Error messages :

# /etc/rc.d/pf restart
Disabling pf
pf disabled
.
Enabling pf
no IP address found for lo1:network
/etc/pf.conf:4: could not parse host specification
no IP address found for lo1:network
/etc/pf.conf:5: could not parse host specification
pfctl: Syntax error in config file: pf rules not loaded
pf enabled
.

Side Effect :

When running "Ports Jail" terminal with portsnap or installation, it will failed because there's not internet connection present.

Why :

The interface "lo1:network" is missing due to abnormal shutdown of "portjail" service.

FreeBSD - lspci equivalent command in FreeBSD

Platform :
FreeBSD

Objective :
List or show PCI devices





Command :

FreeBSD - How to change time zone

Platform :
FreeBSD

Objective :
Change the FreeBSD system clock time zone

Command :

tzsetup

vim - How to stop vim creating "tilde" backup files

Vim, aka the Programmer's Editor, by default creates backup files (ends with a tilde character) whenever editing file. E.g. myfile~, another_file~, yet_another_file~ and etc.

After some time, this generates too many backup laying around the file system. Too messy. This is how to stop vim create these backup files :

Perl - How to find out what Core Modules installed

Perl comes with a set of core modules. Perl core modules comes with default installation.
E.g. :
- Env
- File::Spec
- File::Basename
- Time::localtime

These are just some of the gems to a system administrator. So, how to find out what core modules are included with your perl installation?




Here's how :

FreeBSD - How to change screen to use BASH

Purpose :
Make screen, the virtual terminal program, changes the user's default shell from tcsh to BASH when starting.

Command :

FreeBSD - How to create big huge files

Platform :
FreeBSD

Purpose :
Create big files for testing purpose.

Command :

dd

Bash - How to output all (stdout & stderr) into log file in Bash

Purpose :
When scripting Bash scripts, often we'll need to output all stdout & stderr of a particular command into a log file, for logging purposes or diagnostic purposes.






Command :

FreeBSD - How to check device or CPU performance

Platform :
FreeBSD

Purpose :
Monitoring disk read/write activity.

Command :
iostat


Installation :
The "iostat" command comes with the base installation.

Useful switches :
-w == update frequency, in seconds
-d == only show devices, hdd related
-C == show CPU activity only

Example :

ssh - How to pipe output from local to remote server

In Bash, with pipe (the "|" symbol) and ssh makes a good combination of server administration tool, securely. Some examples :

FreeBSD - How to test newsyslog for systax error

Platform :
FreeBSD

Purpose :
Syntax checking after creating a new logrotate in "newsyslog"

Command :
newsyslog


Installation :
The "newsyslog" log rotation program comes with the base installation.

Useful switches :
-n == DO NOT actually do the logrotate. Instead, show what will be perform
-vv == verbose on what newsyslog is doing

Example :