Posts Tagged ‘small’

How to build Linux logging bash shell script write_log, logging with Named Pipe buffer, Simple Linux common log files logging with logger command

Monday, August 26th, 2019

how-to-build-bash-script-for-logging-buffer-named-pipes-basic-common-files-logging-with-logger-command

Logging into file in GNU / Linux and FreeBSD is as simple as simply redirecting the output, e.g.:
 

echo "$(date) Whatever" >> /home/hipo/log/output_file_log.txt


or with pyping to tee command

 

echo "$(date) Service has Crashed" | tee -a /home/hipo/log/output_file_log.txt


But what if you need to create a full featured logging bash robust shell script function that will run as a daemon continusly as a background process and will output
all content from itself to an external log file?
In below article, I've given example logging script in bash, as well as small example on how a specially crafted Named Pipe buffer can be used that will later store to a file of choice.
Finally I found it interesting to mention few words about logger command which can be used to log anything to many of the common / general Linux log files stored under /var/log/ – i.e. /var/log/syslog /var/log/user /var/log/daemon /var/log/mail etc.
 

1. Bash script function for logging write_log();


Perhaps the simplest method is just to use a small function routine in your shell script like this:
 

write_log()
LOG_FILE='/root/log.txt';
{
  while read text
  do
      LOGTIME=`date "+%Y-%m-%d %H:%M:%S"`
      # If log file is not defined, just echo the output
      if [ “$LOG_FILE” == “” ]; then
    echo $LOGTIME": $text";
      else
        LOG=$LOG_FILE.`date +%Y%m%d`
    touch $LOG
        if [ ! -f $LOG ]; then echo "ERROR!! Cannot create log file $LOG. Exiting."; exit 1; fi
    echo $LOGTIME": $text" | tee -a $LOG;
      fi
  done
}

 

  •  Using the script from within itself or from external to write out to defined log file

 

echo "Skipping to next copy" | write_log

 

2. Use Unix named pipes to pass data – Small intro on what is Unix Named Pipe.


Named Pipe –  a named pipe (also known as a FIFO (First In First Out) for its behavior) is an extension to the traditional pipe concept on Unix and Unix-like systems, and is one of the methods of inter-process communication (IPC). The concept is also found in OS/2 and Microsoft Windows, although the semantics differ substantially. A traditional pipe is "unnamed" and lasts only as long as the process. A named pipe, however, can last as long as the system is up, beyond the life of the process. It can be deleted if no longer used.
Usually a named pipe appears as a file, and generally processes attach to it for IPC.

 

Once named pipes were shortly explained for those who hear it for a first time, its time to say named pipe in unix / linux is created with mkfifo command, syntax is straight foward:
 

mkfifo /tmp/name-of-named-pipe


Some older Linux-es with older bash and older bash shell scripts were using mknod.
So idea behind logging script is to use a simple named pipe read input and use date command to log the exact time the command was executed, here is the script.

 

#!/bin/bash
named_pipe='/tmp/output-named-pipe';
output_named_log='
/tmp/output-named-log.txt ';

if [ -p $named_pipe ]; then
rm -f $named_pipe
fi
mkfifo $named_pipe

while true; do
read LINE <$named_pipe
echo $(date): "$LINE" >>/tmp/output-named-log.txt
done


To write out any other script output and get logged now, any of your output with a nice current date command generated output write out any output content to the loggin buffer like so:

 

echo 'Using Named pipes is so cool' > /tmp/output-named-pipe
echo 'Disk is full on a trigger' > /tmp/output-named-pipe

  • Getting the output with the date timestamp

# cat /tmp/output-named-log.txt
Mon Aug 26 15:21:29 EEST 2019: Using Named pipes is so cool
Mon Aug 26 15:21:54 EEST 2019: Disk is full on a trigger


If you wonder why it is better to use Named pipes for logging, they perform better (are generally quicker) than Unix sockets.

 

3. Logging files to system log files with logger

 

If you need to do a one time quick way to log any message of your choice with a standard Logging timestamp, take a look at logger (a part of bsdutils Linux package), and is a command which is used to enter messages into the system log, to use it simply invoke it with a message and it will log your specified output by default to /var/log/syslog common logfile

 

root@linux:/root# logger 'Here we go, logging'
root@linux:/root # tail -n 3 /var/log/syslog
Aug 26 15:41:01 localhost CRON[24490]: (root) CMD (chown qscand:qscand -R /var/run/clamav/ 2>&1 >/dev/null)
Aug 26 15:42:01 localhost CRON[24547]: (root) CMD (chown qscand:qscand -R /var/run/clamav/ 2>&1 >/dev/null)
Aug 26 15:42:20 localhost hipo: Here we go, logging

 

If you have took some time to read any of the init.d scripts on Debian / Fedora / RHEL / CentOS Linux etc. you will notice the logger logging facility is heavily used.

With logger you can print out message with different priorities (e.g. if you want to write an error message to mail.* logs), you can do so with:
 

 logger -i -p mail.err "Output of mail processing script"


To log a normal non-error (priority message) with logger to /var/log/mail.log system log.

 

 logger -i -p mail.notice "Output of mail processing script"


A whole list of supported facility named priority valid levels by logger (as taken of its current Linux manual) are as so:

 

FACILITIES AND LEVELS
       Valid facility names are:

              auth
              authpriv   for security information of a sensitive nature
              cron
              daemon
              ftp
              kern       cannot be generated from userspace process, automatically converted to user
              lpr
              mail
              news
              syslog
              user
              uucp
              local0
                to
              local7
              security   deprecated synonym for auth

       Valid level names are:

              emerg
              alert
              crit
              err
              warning
              notice
              info
              debug
              panic     deprecated synonym for emerg
              error     deprecated synonym for err
              warn      deprecated synonym for warning

       For the priority order and intended purposes of these facilities and levels, see syslog(3).

 


If you just want to log to Linux main log file (be it /var/log/syslog or /var/log/messages), depending on the Linux distribution, just type', even without any shell quoting:

 

logger 'The reason to reboot the server Currently was a System security Update

 

So what others is logger useful for?

 In addition to being a good diagnostic tool, you can use logger to test if all basic system logs with its respective priorities work as expected, this is especially
useful as I've seen on a Cloud Holsted OpenXEN based servers as a SAP consultant, that sometimes logging to basic log files stops to log for months or even years due to
syslog and syslog-ng problems hungs by other thirt party scripts and programs.
To test test all basic logging and priority on system logs as expected use the following logger-test-all-basic-log-logging-facilities.sh shell script.

 

#!/bin/bash
for i in {auth,auth-priv,cron,daemon,kern, \
lpr,mail,mark,news,syslog,user,uucp,local0 \
,local1,local2,local3,local4,local5,local6,local7}

do        
# (this is all one line!)

 

for k in {debug,info,notice,warning,err,crit,alert,emerg}
do

logger -p $i.$k "Test daemon message, facility $i priority $k"

done

done

Note that on different Linux distribution verions, the facility and priority names might differ so, if you get

logger: unknown facility name: {auth,auth-priv,cron,daemon,kern,lpr,mail,mark,news, \
syslog,user,uucp,local0,local1,local2,local3,local4, \
local5,local6,local7}

check and set the proper naming as described in logger man page.

 

4. Using a file descriptor that will output to a pre-set log file


Another way is to add the following code to the beginning of the script

#!/bin/bash
exec 3>&1 4>&2
trap 'exec 2>&4 1>&3' 0 1 2 3
exec 1>log.out 2>&1
# Everything below will go to the file 'log.out':

The code Explaned

  •     Saves file descriptors so they can be restored to whatever they were before redirection or used themselves to output to whatever they were before the following redirect.
    trap 'exec 2>&4 1>&3' 0 1 2 3
  •     Restore file descriptors for particular signals. Not generally necessary since they should be restored when the sub-shell exits.

          exec 1>log.out 2>&1

  •     Redirect stdout to file log.out then redirect stderr to stdout. Note that the order is important when you want them going to the same file. stdout must be redirected before stderr is redirected to stdout.

From then on, to see output on the console (maybe), you can simply redirect to &3. For example
,

echo "$(date) : Do print whatever you want logging to &3 file handler" >&3


I've initially found out about this very nice bash code from serverfault.com's post how can I fully log all bash script actions (but unfortunately on latest Debian 10 Buster Linux  that is prebundled with bash shell 5.0.3(1)-release the code doesn't behave exactly, well but still on older bash versions it works fine.

Sum it up


To shortlysummarize there is plenty of ways to do logging from a shell script logger command but using a function or a named pipe is the most classic. Sometimes if a script is supposed to write user or other script output to a a common file such as syslog, logger command can be used as it is present across most modern Linux distros.
If you have a better ways, please drop a common and I'll add it to this article.

 

Helpful Hints For Starting A Small WordPress Website or Ecomerce Business

Wednesday, August 14th, 2019

hints-for-starting-wordpress-site

Wordpress is the web application collection of PHP program behind thirty four percent (43%) of the internet’s websites, and fifteen percent (50%) of the top one hundred websites in the world, so if you’re considering it for your website then you’re perhaps thinking in the right direction. Small start-up projects a community website or even a small personal owned blog or mid to even large business presentation site  can benefit greatly from setting up their Web Platrform or Ecommerce shops on a WordPress website platform (that of itself depends just on a small number of technologies such as a Linux server with a Web Server installed on it to serve PHP as well as some kind of Linux host installed Database  backend engine such as MYSQL / PostgreSQL etc. …

But if you really want to create a successful ecommerce website on WordPress, that can seem a little intimidating at first as the general complexity to start up with WordPress looks very scary in the beginning. However in this article I’ll point to fewhelpful hints should get you off on the right foot, and make your entry into the world of Wodpress / WP Ecommerce a little easier and less scary.

This article is to be less technical than expected and in that will contrast slightly with many of the articles on this blog, the target audience is more of Web Marketing Manager or a Start-up Search Engine Optimization person at a small personal project or employed in the big bad corporate world.This is no something new that is going to be outlined in this article but a general rules that are known for the professional SEO Gurus but is most likely to be helpful for the starting persons.

If you happen to be one of these you should know you have to follow a set of well known rules on the website structure text, descriptions, text, orientation, ordering of menus and data etc. in order to have the WordPress based website running at full speed attracting more visitors to your site.
 

Photos
 

 

Importance of Photos on a Webiste
Although the text for your website is very important – more on that later – when a user first opens up your website in their browser, their eyes are going to be caught by the images that you have laid out on your website. Not using images is a big mistake, since it bores users’ eyes and makes your website seem amateur and basic, but using low quality images or irrelevant images can also harm your chances of appearing authentic to a user (yes here on this blog there are some of this low quality pictures but this is due to fact this website is more of information blog and not ecommerce. Thus at best case always make sure that you find the best, high-quality images for your website – make sure that you have the correct rights to use the images as well (as copyright infrignmenets) could cause you even a law suits ending in hundred or thousand dollar fines or even if this doesn't happen any publicity of such would reduce your website indexing rating. The images placed should always be relevant to your website. If you find a breath-taking sunset or tech-gadget picture, that’s great, but maybe not for your healthy food ecommerce store, but for your personal ranting or describing a personal experience.

 

Product Photos


Assuming that sooner or later even if you have a community website you will want to monerize it to bring back to yourself in material form at least part of the many years effort to bring the site to the web rank gained.
Leading on from that point, you’re going to be selling or advertise items – that’s the whole point of ecommerce. But users often find ads / online shopping frustrating due to not being able to properly see and understand what they’re buying before they make their purchase. This can lead to ‘buyer’s remorse’, and, consequently, refunds galore, which is not what you want. Make sure that images of your products are always available and of a high quality – investing in a fairly high quality camera might be a good idea – and consider many pictures for different angles or even rotating images so that the user can decide for themself which angle they want to look at.

 

Engaging Descriptions


“I can guarantee that you can’t remember the last five product descriptions you read – not even word-for-word, but the general ideas and vocabulary used will have been tossed into your short-term memory and forgotten in an instant. This is where your website can shine, and become better than ninety percent of those lingering on the internet,” Matthew Kelly, a project manager at WriteMyX and NextCoursework, suggests, “since putting effort into writing your product descriptions and making them lively and engaging will make your website memorable, and your subscribers will turn helpfully soon loyal customers will be more likely to come back time and time again and become repeat business, as well as mention you to their friends (social mounth to mouth marketing) and that way working as free advertising for you and making your website incredibly effective.”

 

Mobile-Friendly

 

Which device is most used to check email Laptop / PC or Mobile statistics as of year 2019

These days with the bloom of Mobile Devices that are currently overrunning the user of normal Desktop PCs, Laptops and Tablets and this trend is likely to stay and even increase, “If your website isn’t mobile-friendly in this day and age, then you won’t get anywhere with it.” Anne Baker, a marketer at BritStudent and Australia2Write, states. “Most people use their phones when they access websites, especially when they go shopping on the internet.

Statistics on user stay (secs / mins) stay on a website from Desktop PC and Mobile devices

On WordPress, this means finding a more recent theme – an older theme, maybe four-five years old, will probably not support mobile, and you just can’t afford to lose out on the mobile market.” In short, find yourself a mobile-friendly theme or install the right WordPress Pluguin that will enable you to have a Mobile Friendly theme in case if blog is accessed from a Mobile Dev or many of your customers will become frustrated with the badly formatted ‘mobile’ version of your website that they end up using, which might be for instance meant for a much larger screen. It can also ruin the atmosphere (experience) created at the accessed user site and have negative impact on your audience opion of your site or business. This is even more the case  if your website or webapp is targetting to be modern and keeping with the times – or especially if it deals with IT and electronics (where the competition is huge)!

 

Registration

 

Registration Ecommerce website

Registration form (Sign Up) on a website and the overall business cycle idea behind web product or business is of critical importance as this is the point that will guarantee intimidation with the customer, failing to have the person be engaged will quickly make your website rank lower and your producs less wanted. The general rule here is to make your registration be an easy (to orientate for the user) and be present on a very visible place on the site.

Registration steps should be as less as possible as this might piss off the user and repel him out of the site before the registration is completed. Showing oportunity to register with a Pop-Up window (while the user clicks on a place showing interest for the produce might be useful in some cases but generally might also push the user back so if you decide to implement it do it with a lot of care (beware of too much aggressive marketing on our site).

An example


The registration process should be as intimidating as possible to leave joy in the user that might later return and log in to your site or ecommerce platform, e.g. be interested to stay for a longer time. The marketing tactic aiming to make the user stay for a longer time on the website (dragging his attention / interest to stuff)  is nothing new by the way as it is well known marketing rule integrated in every supermarket you buy groceries, where all is made to keep you in the shop for as longer as possible. Research has shown that spending longer time within the supermarket makes the user buy more.

 

Returning customers can be intimidated with membership or a free gift (be it even virtual picture gift – free email whatever) or information store place could be given or if products are sold, registration will be obligatory to make them use their payment method or delivery address on next login to easify the buy out process. But if registration is convoluted and forced (e.g. user is somehow forced to become meber) then many customers will turn away and find another website for their shopping needs. Using a method like Quora’s ‘login to see more’ in that case might be a good idea even though for me this is also a very irritating and irritating – this method however should never be used if you run a ecommerce selling platform, on ecommerce site gatekeeping will only frustrate customers. Login is good to be implmeneted as a popup option (and not taking too much of the screen). Sign up and Login should be simplistic and self-explanatory – always not required but optioned and user should get the understanding of the advantage to be a member of the website if possible before the sign up procedure. Then, customers are more likely to sign up and won’t feel like they’ve been pushed into the decision – or pushed away, as the case may be.

Katrina Hatchett works as a lifestyle blogger at both Academic Brits and Assignment Help, due to a love of literature and writing, which she has had since youth. Throughout her career, she has become involved with many projects, such as writing for the PhD Kingdom blog.

A small journey to Obrochishte and Batovo villages

Monday, October 26th, 2009

Thanks to Ceco (a young orthodox friend of mine, a really cool guy), we made a nice quick organized journey to Obrotishte. The main purpose of the trip was to go to a liturgy to the Church there in Obrotishte and also to visit the Hieromonk Philip (Filip) who is at the present moment priest in the Church there. Father Philip is a really interesting monk, he is currently 28. As most people could understand it’s really unusual this days for someone to become a monk, it’s even more unusual for somebody to become a monk in such a young age. Father Philip has been a monk in Troyan Monastery which presently is among the largest operating monasteries at the moment in Bulgaria. Father Filips is a wonderful person, the church service started a bit later than usual in around 09:20 in the morning, what struck me was that the whole service was held in plain understandable modern Bulgarian language, that shined some light (understanding) on the liturgy and was possibly better than in Church Slavonic language, which is hardly understandable for us Bulgarians in the present age. Another good thing I loved about the service, that Father Filip led the liturgy and accomplised all the priest prayers and entreats in a slow understandable way. Seems like the young monk and a father is a real church father, because he was absolutely kind and loving to me Ceco and Rumiana (a christian girl we picked up from another village before we went to the service in Batovo). Another kind thing from Father Filip was that he refused to get any money for writting some names which are usually mentioned on the next liturgy in front of God on the Holy Altar, for the living (that God forgives their sins, and grants them good health, and success in their works) and for the dead (For God to forgive their sins and remember them in it’s kingdom). After the wonderful Church service we get into Ceco’s car with Father Filip and went and had a nice evening and had a nice lunch in a small restaurant in one of the nearby villages to Obrochishte. We also had a nice talk with the father and with Ceco about different things concerning our christian orthodox faith and other spiritual talks. I’m thankful to God for granting me such a wonderful day. After the nice lunch time, we went to Batovo (A village situated North-East in Dobrudja’s region). Batovo is famous with Batovo’s river which flows directly through the village, another thing to see in the village is a holy spring, some nice woods. The village itself is also a nice place to be. They have two springing water fountains one of which seems to be built up from communists during the communist atheist regime in Bulgaria. It’s a real miracle evidencing God’s disapproval for the communists because soon after the springing fountain has been built by the communists it run dry. Hieromonk Philip has prayed near the dried up fountain to God, that God gives his blessing from heaven and allows this dried up water spring to become a springing one that would be a springing place from now on unto the ages of ages. After that we moved on to the center of Batovo’s village where we met a nice gypsy family (romi as we call them in Bulgaria), it was an interesting thing that this people were deeply religious. They had a deep hunger for God they shared that they do attend both evangelical and orthodox church to light up candles or pray and they don’t understand the difference. Father Philip has briefly explained the difference and explained the importance to attend the true church of our Lord Jesus Christ which is the orthodox church and told them if the guys have more questions they could go anytime to the Church in Obrochishte and he would answer them as many questions relating faith as he could. The discussions between the monk me, Ceco, Rumiana and the father was a real blessings, Praise the Lord! However all isn’t perfect and life is far away from bed of roses. On our way back while we were traveling with Ceco and Rumiana my aunt called to inform me my grandma is having difficulties with her speaking (which as she said could be caused by a heart strike… That struck me light a lightining from a blue sky… I got desperated, thanksfully Rumiana and Ceco probably prayed for me and my grandma because presently she is a bit better. Still we have to see how my beloved grandma would be tomorrow after she has a sleep. I’m really concerned for her because she is one of the people that cares for me the most in this life. She loves we like she loves her soul, the same strange love that Jonahattan and David shared in the story told in our Old Testament. I and guess we the christians should learn from my grandmother’s godliness and christian life. She is one of the few that possesses God this days, as she is saying often she is ready to give her soul for me just like our Lord Jesus Christ has loved us so much that he gave his life for us the sinners … I just hope and pray that God hears my and my christian fellow mate prayers and grant my grandma good health! Thanks to God for everything! Just to clause the post I have to mention my big thanks to Lily and Plamen a friends of mine who sustained me this two days with care, talks and prayers. I just pray God helps them the same as they had helped me!

Howto install and configure Local DHCP Server for small LAN local network on FreeBSD

Monday, September 21st, 2009

Since some time ago, I’ve been planning to install a DHCP server to automatically assign the IP addressesof the hosts in my tiny local network.
Here is how I did it:
First I had to install:
the port isc-dhcpd31-server
Execute the commands:# cd /usr/ports/net/isc-dhcp31-server;# make install cleanFor some reason the dhcpd reason didn’t get created, so I have to issue.pw add user dhcpd;After which use vipw to change the default shell for the dhcpd user to /usr/sbin/nologin aswell as the default user home directory to /var/empty
Next I used the following dhcpd.conf file:
— SNAP —option domain-name “pc-freak.net”;option domain-name-servers 83.228.92.2, 83.228.92.2;default-lease-time 600;max-lease-time 7200;# Use this to enble / disable dynamic dns updates globally.ddns-update-style ad-hoc;# Use this to send dhcp log messages to a different log file (you also# have to hack syslog.conf to complete the redirection).log-facility local7;# No service will be given on this subnet, but declaring it helps the # DHCP server to understand the network topology.subnet 10.152.187.0 netmask 255.255.255.0 {}subnet 192.168.0.0 netmask 255.255.255.0 { range 192.168.0.2 192.168.0.255; option domain-name-servers 192.168.0.1; option domain-name “pc-freak.net”; option routers 192.168.0.1; option broadcast-address 192.255.255.255; default-lease-time 3600; max-lease-time 7200;}# the lines below enables you to assign specific IP addresses depending on# machine’s MAC addresshost jericho { hardware ethernet 00:13:2a:33:7d:1e; fixed-address 192.168.0.2;}host noah { hardware ethernet 00:0b:e4:c9:7b:59; fixed-address 192.168.0.4;}— END —
You might need to change some of the IP addresses the conf above is configured for my local networkwhich is in the IP range 192.168.0.2 to 192.168.0.255.
The above conf file’s name servers are my ISP’s nameservers ns.bergon.net and ns1.bergon.netThe variable broadcast-address is the range in which the DHCPD servers will broadcast and eventuallyassign IP addresses.
routers variable sets your network default router in my case it’s my local gateway.
range variable is self explanatory.
subnet is the subnet in which your network is.
max-lease-time is the time interval in which a DHCP IP reassign occurs
default-lease-time the default time on which IP reassign occurs
The rest could be red in the commentaries above the variables:
To make dhcpd log in a separate file it’s also necessery to edit your /etc/syslog.confand change the line
*.notice;authpriv.none;kern.debug;lpr.info;mail.crit;news.err; /var/log/messageswith*.notice;authpriv.none;kern.debug;lpr.info;mail.crit;news.err;local7.!*; /var/log/messages
as well as add:
local7.* /var/log/dhcpd to /etc/syslog.conf.
The above changes in syslog.conf should foce syslogd to log to /var/log/dhcpd instead of stuffing your /var/log/messages withdhcpd log output
It’s also necessary to create /var/log/dhcpd’s file:
Execute: touch /var/log/dhcpd as well as restart the syslogd
/etc/rc.d/syslogd restart .
Futhermore execute:
echo ‘dhcpd_enable=”YES”‘ >> /etc/rc.confecho ‘dhcpd_iface=”rl0″‘ >> /etc/rc.conf
The above as you probably know will schedule isc-dhcpd to start up every time your system boots.
Well you should be now having a shiny spreading dhcpd service in your local network.
Enjoy and Praise God 🙂 !
END—–