How to Find a Specific String or Word in Files and Directories in Linux

Many times we need to search for a particular string which may be present in multiple files. In this article we'll see which commands to use to find all the files that contains a particular string or Word.
It is a powerful regular expression search tool. At a basic level , it will match an input string with the list of files that contain that string.Below is the syntax and the example.
grep 'string' directory-path/*.*
#Example
grep 'config' hadoop-2.6.5/etc/hadoop/*.*
Running the above code gives us the following result −
hadoop-2.6.5/etc/hadoop/capacity-scheduler.xml: <configuration>
hadoop-2.6.5/etc/hadoop/core-site.xml:<configuration>
hadoop-2.6.5/etc/hadoop/hadoop-policy.xml:<configuration>
hadoop-2.6.5/etc/hadoop/hdfs-site.xml:<configuration>
hadoop-2.6.5/etc/hadoop/httpfs-site.xml:<configuration>
hadoop-2.6.5/etc/hadoop/kms-acls.xml:<configuration>
hadoop-2.6.5/etc/hadoop/kms-site.xml:<configuration>
hadoop-2.6.5/etc/hadoop/mapred-site.xml.template:<configuration>
hadoop-2.6.5/etc/hadoop/ssl-client.xml.example:<configuration>
hadoop-2.6.5/etc/hadoop/ssl-server.xml.example:<configuration>
hadoop-2.6.5/etc/hadoop/yarn-site.xml:<configuration>
In this case we mention the r switch, which allows for a recursive search along all the subdirectories of the path given.
grep -r 'string' directory-path/
$ grep -r 'done' hadoop-2.6.5/
Running the above code gives us the following result −
hadoop-2.6.5/sbin/slaves.sh:done
hadoop-2.6.5/sbin/distribute-exclude.sh:done
hadoop-2.6.5/sbin/yarn-daemon.sh:done
hadoop-2.6.5/sbin/kms.sh:done
hadoop-2.6.5/sbin/httpfs.sh:done
hadoop-2.6.5/sbin/refresh-namenodes.sh: done
hadoop-2.6.5/sbin/refresh-namenodes.sh: echo "Refresh of namenodes done."
hadoop-2.6.5/sbin/mr-jobhistory-daemon.sh: done
hadoop-2.6.5/sbin/hadoop-daemon.sh:done
We can also search for multiple words by using the egrep command with | character. In the below example we are searching for files containing either the word config or the word comma.
egrep -r 'word1|word2' directory-path/
#Example
egrep -r 'config|comma' hadoop-2.6
Running the above code gives us the following result −
hadoop-2.6.5/etc/hadoop/capacity-scheduler.xml:<configuration>
hadoop-2.6.5/etc/hadoop/capacity-scheduler.xml:</configuration>
hadoop-2.6.5/etc/hadoop/core-site.xml:&tl;?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
hadoop-2.6.5/etc/hadoop/core-site.xml:<configuration>
hadoop-2.6.5/etc/hadoop/core-site.xml:</configuration>
hadoop-2.6.5/etc/hadoop/hadoop-policy.xml:<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
hadoop-2.6.5/etc/hadoop/hadoop-policy.xml:<configuration>
hadoop-2.6.5/etc/hadoop/hadoop-policy.xml: The ACL is a comma-separated list of user and group names. The user and
hadoop-2.6.5/etc/hadoop/hadoop-policy.xml: The ACL is a comma-separated list of user and group names. The user and
hadoop-2.6.5/etc/hadoop/hadoop-policy.xml: The ACL is a comma-separated list of user and group names. The user and
hadoop-2.6.5/etc/hadoop/hadoop-policy.xml: The ACL is a comma-separated list of user and group names. The user and
hadoop-2.6.5/etc/hadoop/hadoop-policy.xml: The ACL is a comma-separated list of user and group names. The user and
hadoop-2.6.5/etc/hadoop/hadoop-policy.xml: <description>ACL for AdminOperationsProtocol. Used for admin commands.
hadoop-2.6.5/etc/hadoop/hadoop-policy.xml: The ACL is a comma-separated list