The grep command means Global Regular Expression Print. This Linux command is one of the most useful commands out there. Below are some basic examples: grep ‘word’ filenamegrep ‘word’ filename1 filename2 filename3grep ‘string1′ string2’ filenamecat filename | grep ‘something’command | grep ‘something’ Next example, you can search for the user ‘tom’ in the Linux passwd […]
Author Archives: rgm
How to change the default SSH port in MacOS using Terminal
This is simple. Open a terminal and follow the steps below. This worked for me on MacOS 10.13.6 Open the Terminal. Run sudo vim /etc/services Enter your password Find the lines assigned to port 22, something like the image below Replace both ports 22 with your desired ssh port using a number between 1024 and […]
Remote to your office computer from home using SSH and reverse port forwarding
This is easier than what it seems. Follow the steps below in order. Make sure you know your home public IP. Find this info on your home router/modem or do a search in Google “What’s my ip”. Note this IP address. More coming soon!
Linux df command line brief examples
df is a Linux command for for reporting file system disk usage on a Linux system. While brewing coffee at home I found the following. How to view disk usage using df command? Simple! Simplest way is just to type df on the command line and you should get the below output: Filesystem […]
Runlevels Linux Learn more simple table
Hola! Each runlevel has a certain number of services stopped or started, giving the user control over the behavior of the machine. Conventionally, seven runlevels exist, numbered from zero to six. While brewing coffee at home I found the difference between runlevels in Linux. See below. Runlevel Mode Definition 0 Halt Shuts down the system. […]
Default Apache virtual host file in Ubuntu
I was asked the other day ‘How does the default Apache virtual host file looks like?’ I was having my Peruvian coffee and decided to place below the default Apache virtual host file in this post for any future reference. <VirtualHost *:80> ServerName www.example.com ServerAdmin webmaster@localhost DocumentRoot /var/www/html ErrorLog ${APACHE_LOG_DIR}/error.log CustomLog ${APACHE_LOG_DIR}/access.log combined </VirtualHost> Super […]
Linux File Systems ext2, ext3 and ext4
While having coffee at home I decided to put this table together regarding Linux File Systems and their differences. Let me know if I’m missing something. Ext2 Ext3 Ext4 Stands for Second Extended file system. Stands for Third Extended file system. Stands for Fourth Extended file system. Introduced in 1993. Introduced in 2001. Introduced in […]
API requests types brief explanation
API is an Application Programming Interface which is a way that allows communication between two applications using a set of rules. While having a great coffee from Bolivia I found the following API requests types. The main Web Service APIs are: SOAP (Simple Object Access Protocol) uses XML to transfer sets of information in the […]
Difference between Inner Join and Outer Join in SQL
An inner join it is the most common kind of join, so common that SQL doesn’t actually make us say “inner join” to do one. An outer join returns a set of records or rows that include what an inner join would return, but also includes other rows for which no corresponding match is found in the […]
Copying files rsync Linux use of “/” at the end of path
Hello, sometimes we need to copy files and we are not sure when to use “/ ” at the end of the path. Copying files rsync while brewing coffee at home this is what I found. Check this useful summary: