Variables in Bash “: command not found”

Bash is like the very complicated language, even a space can make a syntax error. But, when you get into it often, you will get a hang of it and it will be easy. This post is a solution to one of the most common problems that happen to a newbie in Bash and it’s about a single whitespace. Here is a sample Bash file : a = 50 echo…

Append Contents to Files in Bash

In Bash, we can add contents to file easily using the > character. Like this : echo "myContents" > ~/myfile.txt What if you want to append contents to the file without overwriting ? The easiest way to do this is change the “>” to “>>”. Just by making this small change, appending will be done : echo "myContents" >> ~/myfile.txt Even if the file doesn’t exist, Bash will create one…

if, else, elif Conditions in Bash

All programming languages have the if & else conditions and they’re different in syntax according to each programming languages. In Bash, it’s really different and even a small space can cause syntax errors. So, you have to be careful while writing Bash code. In this post, I’ll give you many examples on how to use if and else conditions in Bash. if, else a="AC" if [ $a = "AC" ];…

Creating a File with Contents in Bash

It’s really easy to create a file in Bash with cat and > : cat "/home/simsu/file.txt" > "/home/simsu/file.txt" But, what if you want to add contents to file too ? In this case, we can use cat and echo. Here’s how we do it in echo : echo "My File, My Choice" > "/home/simsu/file.txt" But, there’s a problem with doing like this. Since there is an option to limit the…

Check if Bash Script is ran by Root User

Root users have the privilege to do administrative stuff in Linux and if you’re creating a Bash script to install something or change something in the system, you need root. So, checking whether the script was ran by root is very important. if [ "$EUID" -ne 0 ] then echo "Please run as root" exit fi There is no else condition. You can add the code which will does stuff…

Replace Strings in Files With PHP & Python

There are softwares already that helps to replace a string in a file. Suppose, if you’re making a program that requires saving some data in to a file. By “adding”, the program is actually replacing a word. Let’s see how it’s done in PHP & Python. This is the file where we are going to replace the word : thisWord I got thisWord for making it thatWord replace thisWord already…