use grep to search in a file code example

Example 1: read string by string in file in linux

grep 'word' filename
grep 'word' file1 file2 file3
grep 'string1 string2'  filename
cat otherfile | grep 'something'
command | grep 'something'
command option1 | grep 'data'
grep --color 'data' fileName

Example 2: how to search keyword in linux

grep -w phoenix *