touch hello.sh #! /bin/bash #this is a comment echo "hello world" ------------------------------------------------------------------------------------------------------- print to screen : echo echo 'hey' echo hello echo "hey " variables are not parsed in single quoted echo -------------------------------------------------------------------------------------------------- system variables : env, printenv , set command echo $HOME echo $BASH echo $BASH_VERSION echo $PWD echo $PATH ------------------------------------------------------------------------------------------------------- user defined variable : varname=valueofvar name=myname echo my name is $name variable naming:not starting with number and no special characters except _ ---------------------------------------------------------------------------------------------------------- reading user input: read echo enter name read name echo hello $name echo enter age and sex r