Pattern searching using grep

The command g/RE/p stands for globally search for the regular expression (RE) and print the line. The return statuses are 0 for success, 1 for pattern not found, and 2 for file not found:

    $ ps -ef | grep root

The preceding command will show all processes running currently whose user ID is root.

    $ ll /proc | grep "cpuinfo"

The preceding command will show the file with the name cpuinfo from the /proc directory.

    $ grep -lir "text" *          // show only file names containing text //   
    $ grep -ir "text" dir_name    // show lines of files //

We will try the following commands on file love.txt:

We will create a new file sample.txt, as follows:

Apple Fruit 5  4.5

Potato Vegetable 4  .5

Onion Vegetable .3  8

Guava Fruit 5  1.5

Almonds Nuts 1 16

Tomato Vegetable 3  6

Cashew Nuts 2  12

Mango Fruit 6  6

Watermelon Fruit 5  1

We will try the following commands on the sample.txt file: