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BASH - Get a SubString

To cut portions of a string:

#!/bin/bash
Str="My name is Peter"
subStr=${Str:0:6}
echo $subStr

This script should print out “My nam” as its output.

The parameter expansion takes the form ${VAR_NAME:S:L}.

Here, S denotes starting position and L indicates the length.

Extracting Substrings Using Cut

cut can be used to ‘cut’ a portion of a string, aka the substring.

#!/bin/bash
Str="My name is Peter"
#subStr=${Str:0:6}
 
subStr=$(echo $Str| cut -d ' ' -f 1-3)
echo $subStr

In general to concatenate two variables you can just write them one after another:

a='Hello'
b='World'
c="${a} ${b}"
echo "${c}"
> Hello World

or

foo="Hello"
foo="${foo} World"
echo "${foo}"
> Hello World