In the first example, I will search for the user “root the Linux passwd file. To search the /etc/passwd file for the user “root”, you need to enter the following command:
grep root /etc/passwdGiven below is the sample Output: root:x:0:0:root:/root:/bin/bash
Using grep to search only for words
When you are searching for abc, grep will match all sorts of things, viz., kbcabc, abc123, aarfbc35 and lots more combinations without obeying word boundaries. You can compel the grep command to select only those lines that contain matches to form whole words (those that match only abc word), as shown below:
grep -w "abc" fileUsing grep to search two different words
To search for two different words, you must use the egrep command as shown below:
egrep -w 'word1|word2' /path/to/fileCount lines for matched words
The grep command has the ability to report the number of times a particular pattern has been matched for each file using the -c (count) option (as shown below):
grep -c 'word' /path/to/fileIn addition, users may use the ‘-n’ option preceding each output line with the number of the line in the text file from which it was obtained (as shown below):
grep -n 'root' /etc/passwdGiven below are the Sample outputs: 1:root:x:0:0:root:/root:/bin/bash
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