Filter & IO redirection command.

Grep

grep command is used to find texts from any text input. Passwd file: stores information about all the users in the system.

➔ Finding line which contains word as “root” from /etc/passwd file.

➔ Linux is case sensitive, Root is different that root. Ignoring case in grep with -i option.

➔ To display things except the given word use -v option

Filter Commands

• less: Displays file content page wise or line wise. Ex: less /etc/passwd

• more

• head

• tail

• cut

• sed

I/O redirection

I/O redirection is accomplished using a redirection operator which allows the user to specify the input or output data be redirected to (or from) a file. Note that redirection always results in the data stream going to or coming from a file (the terminal is also considered a file).

➔ Create a file named DevOps tools with below content.

➔ Search for text “tech” replace it with “tools” and redirect output to a new file.

➔ Appending another output in same file with “>>” .

➔ Redirecting only error to a file “2>>”.

➔ Redirecting all the output to a file “&>>”.

Piping

So far we've dealt with sending data to and from files. Now we'll look at a mechanism for sending data from one program to another. It's called piping and the operator we use is ( | ). What this operator does is feed the output from the program on the left as input to the program on the right.

Find

The 'find' command is your go-to tool for locating files and directories in a Linux system. It's versatile, allowing you to search based on name, size, type, and other criteria. Let's dive into the basic usage of the 'find' command.