Table of contents
No headings in the article.
File name conventions
file name can be a maximum of 225 characters
the name may contain alphabets(a-z or A-z), digits(0-9), dots(.), and underscores(_)
system commands or Linux reserve words can not be used for file names
the file system is case-sensitive
ex: var_01 etc.,
comments
use of comments
it is for more understandability and readability
it is used for escape from the code
shell script has two types of comments
single line comment
#this is a single line comment
multi-line comment
<< Suma
hi
hello
Suma
output
Variable
A variable is a character string to which we assign a value. the value assigned could be a number, text, file name, device, or any other type of data
- it is a storage. it can store the value
there are two types of variables
a) system define variables - these are created and maintained by the system i.e Bash
env or printenv to see all system-defined variables usually it shows
VARIABLE_NAME= $VARIABLE_VALUE
ex: FRUIT="apple"
here the variable is defined as FRUIT and the value that has been assigned to the FRUIT variable is "apple"
The value stored in a variable can be accessed by prefixing its name with the dollar ($) sign.
ex: #!/bin/sh
FRUIT = “Pineapple”
echo “My favorite fruit is $FRUIT.”
output: My favorite fruit is Pineapple
echo $shell - it is going to display variable value
b) user-defined variables
as a user, he/she is going to create a variable and also going to assign the values
user-defined vars --(user-defined and set the values)
a = 10 echo $a echo" a variable value is:"${a}
b = 20 echo $b echo" b variable value is:"${b}
c =30 echo $c echo" c variable value is:"${c}
name=Kalyan echo $Kalyan echo "name variable value is:"${name}
