We can run the bash script directly in the terminal.
$ echo "This is a bash script." This is a bash script.
We also can store the script in a file, so that we can run it every time we want without typing the script in terminal.
# !/bin/bash echo "This is a bash script."
We need to update the file permission if we want to run the bash file. We can run this command, and specify the file permission
$ chmod 700 FILE $ ./FILE This is a bash script.
We can run linux command in bash file and run the bash script in the cli.
The bash file will very useful if we want to use some variable or put logics in the script.
- Positional Parameter Variable
# !/bin/bash echo "This is a $1 $2."
we can give a value for
$2 after the run command.
$ ./FILE bash script
- User Defined Variable
# !/bin/bash # define a string value, print as is print1='script' # define a string value, we can add variable inside the double quotes print2="bash $print1" # define a number print3=3 # define a command print4=`clear` echo $script
- Environment Variable
Usually we use
.env file to store the environment variable
operation for variable
# using let let sum=$number1+$number2 # using expr sum=`expr $number1 + $number2` length=`expr length $string`
declaring variable type
# declare an intrger declare -i number number=100
if [ CONDITION ]; then TRUE_COMMANDS else FALSE_COMMANDS fi
while [ CONDITION ] do COMMANDS done
for VARIABLE in LIST do COMMANDS done