Sudo

• It allow a user with proper permissions to execute a command as another user, such as the superuser.

Flags of sudo

• -V : used to check the version.
• -l : used to list which we have to print from current host.
• -v : sudo will update the user’s timestamp, prompting for the user’s password if necessary.
• -h : used to help.
• -k : it used to sudo invalidates the user’s timestamp.
• -K : it used to remove the user’s timestamp entirely.
• -b : it tells sudo to run the given command in the background.
• -p : allows you to override the default password prompt and use a custom one.
• -u : user can run the specified command as a user other than root.
• -s : runs the shell specified by the SHELL environment variable if it is set or the shell as specified in the file password.
• - : indicates that sudo should stop processing command line arguments.

Syntax of sudo

sudo [command]

apt (Advanced Packaging Tool)

• It perform as installation of new software packages, upgrade of existing software packages, updating of the package list index, and even upgrading the entire Ubuntu system.

• Install package
  

sudo apt install <package_name>

• Update package in index

sudo apt update

• Remove a package

sudo apt remove <package_name>

• Upgrade package

sudo apt upgrade

touch

• It is used to create a file, update the modification and access time of each file with the help of touch command.

Syntax of touch

touch <file_name>

Flags in touch

• -a : used to change the access time of a file.
• -m : help you to change only the modification time of a file.
• -r : it update time with reference to the other mentioned command.
• -t : we can change the access time of a file by determining a specified time to it.

cat

• Create a file bye using '>' symbol.
• It can read the data inside the file.

Syntax of cat

• create a file

cat > 'file_name'

• to read a file

cat 'file_name'

less

• It automatically adjust with the width and height of the terminal window.

less 'file_name'