Grep Words From a File

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Q. How do I grep words from a text file under UNIX / Linux / BSD operating systems?

A. grep is a command line text search utility originally written for Unix / Linux / Windows and Mac OS X. You need to use this tool to grep words from a text file.

Find words from a file

To find word from a file use following syntax:
grep “word” {filename}
Find word Orange in the file called data.txt:
$ grep "orange" data.txt
Grep prints all lines containing ‘orange’ from the file data.txt, regardless of word boundaries; therefore lines containing ‘orangeade’ or ‘oranges’ are also printed.

Grep Words Form the File

To print all lines containing ‘orange ‘ as a word (‘orangeade’ and ‘oranges’ will not match):
$ grep -w orange data.txt

Ignore case distinctions with grep

The grep command is case sensitive by default, so this example’s output does not include lines containing ‘Orange’ (with a capital O) unless they also contain ‘orange’. To perform ignore case distinctions use the -i option:
$ grep -i orange data.txt
You can combine all options together to find only ‘orange ‘ as a word with no case distinctions:
$ grep -wi orange data.txt

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

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