grep in UNIX

The grep command searches the given file for lines containing a match to the given strings or words.
By default, grep displays the matching lines. Use grep to search for lines of text that match one or many regular expressions, and outputs only the matching lines.

Syntax:
grep 'word' filename

Example:
In /var/root/, we have a file called 1.txt.
The content in the file is "I am coming from forget code"
grep 'code' /var/root/*

Output:
/var/root/1.txt:I am coming from forget code