Sunday, March 18, 2018

Comparing two files without using DIFF

This is a a short way to compare 2 files on a Unix box without using DIFF. You can remove the option to output it to a file "> file3" if you want to see the output first.

If you want to see the uniq entries without the duplicates then output to a file:


sort file1 file2 | uniq -u > file3

If you want to see just the duplicate entries use "uniq -d" option then output to a file:


sort file1 file2 | uniq -d > file3

Friday, January 06, 2017

WIFI script for systemd init systems

I used the following Steps to create a startup script that will automatically connect my WIFI after a reboot. Not sure if there are more efficient way but this works for me so far. I normally do minimum install so there's no GUI running on my Linux machine. Tested it on Ubuntu 16.10 Yakkety.

Pre requisite
a. Disable network-manager service.
b. You need root access.

1. Create wifi WPA supplicant config appropriate for your Wifi Connection. The example was based on using WPA-Personal (Security Mode).

vi  /etc/wpa_supplicant.conf

        ssid="WIFI SSID (ex FreeWIFI)"
        proto=RSN WPA
        pairwise=CCMP TKIP
        group=CCMP TKIP

2. Create the script that will contains the CLI command that connects the wifi

vi /*path*/
/sbin/wpa_supplicant -Dnl80211 -iwlp2s0 -c/etc/wpa_supplicant.conf &

*Change the *path* to a folder of your choice (do the same on Step 3)
wlp2s0 - is the name of your wifi interface name. Run "ip addr sh" if you're not sure.

3. Create the systemd  init script file

vi /etc/systemd/system/wifi.service
Description=This will and connect the wifi @ startup



4. ADD the systemd init script during Startup using systemctl:

systemctl daemon-reload
systemctl enable wifi.service
systemctl start wifi.service

5. Reboot your system to test if script works



On second note just run nmtui if your network manager is working fine will save you the trouble of manually creating the wpa_supplicant file. The tutorial above works best if you're only connecting to 1 wifi connection and you don't expect the linux box or server to be more elsewhere.

Saturday, November 19, 2016

Task Automation without API through Headless Browser

I've been researching lately on headless browsing as I have this automation idea that can literally put me on early retirement. For those of you who are looking to automate some task but the Site you're relying on don't have any available API to work with then this might solve your problem. Special thanks to my colleague Huy who suggested the idea.

Undertanding Headless Browser:

PhantomJS - This is a good headless browser

CasperJS - You can create simple javascript code using this which makes interaction and navigation with your headless browser so much easier.

Sunday, April 13, 2014

Modify FSTAB on CentOS or RHEL 6 on Bootup

Ever encounter a problem when you can't boot due to corrupted or wrong FSTAB entry. Here's a simple fix



a. At  Grub press any key
b. Press "e" to edit

c. Under kernel parameter Append this command "init=/bin/bash"
d. Press Enter then "b"
e. This will take you directly to #.. Remount the / by typing  mount -o remount,rw /
f.  Edit fstab vi /etc/fstab
g. Save and Reset the system

Saturday, March 02, 2013

Annoying "perl: warning: Setting locale failed"

This post shows a simple way of removing this annoying warning when running perl in linux.

perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LANGUAGE = (unset),
LC_ALL = (unset),
LANG = "en_US.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").


on your home directory:

1. Edit your user bash_profile

vi .bash_profile

2. Insert the following:

export LANGUAGE=en_US.UTF-8

export LANG=en_US.UTF-8
export LC_ALL=en_US.UTF-8

3. Rerun your Bash Profile

. ~/.bash_profile 

Hope this helps.

Sunday, July 24, 2011

FIND and REPLACE TEXT inside a file without using TEXT Editor

FIND and REPLACE TEXT inside a file without using TEXT Editor

You can perform a text replace within a file without using VI or other text editor available on your Unix or Linux box. Below command will help you perform that action. 

Using SED:

Using PERL:

FIND TEXT - Content you want to replace
REPLACE TEXT - New Value of the content

Thursday, July 07, 2011


Fold Long Line files to Finite Width output device 

Ex: fold -b < long_line_file >folded_file

Now the folded_file will  contain output with newlines 
inserted after maximum bytes specified.  This will be 
useful when editing special files. You can do the reverse 
using "expand" command.