To create variable. export DB_USERNAME=dbuser export DB_PASSWORD=secretpwdvalue export DB_NAME=mydb printenv | grep DB echo $DB_NAME "IF YOU WANT TO SEE" export DB_NAME=NEW-DB-NAME "To change new name" if you want to do it permanently you have to use "Vim" vim .bashrc "at …

diff: To find the differences between two files, use diff followed by the file names. For example, diff file1.txt file2.txt will display the lines that differ between “file1.txt” and “file2.txt”. cmp: Use cmp followed by the two file names to check if two files are identical. …

How to use them? ls: To list directories and files in the current directory, simply type ls and press Enter. You can also specify a directory as an argument to list its contents. pwd: Typing pwd and pressing Enter will display the current working directory. cd: To navigate through directories, use …