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#Grab grep pattern after a symbol full

When you had option to show the N lines after match, you have the -B option for the opposite. B is the option which prints the specified N lines before the match. The following example prints the matched line, along with the 3 lines after it. A is the option which prints the specified N lines after the match as shown below. Word - word consists of a sequence of letters, digits and underscores.Įxample to show the difference between WORD and word WORD - WORD consists of a sequence of non-blank characters, separated with white space. You may want to do several navigation in relation to the words, such as: Please create the following demo_text file for this example. You might feel handy if grep can show you not only the matching lines but also the lines after/before/around the match. When doing a grep on a huge file, it may be useful to see some lines after the match. Displaying lines before/after/around the match using grep -A, -B and -C $ grep -iw "is" demo_fileĪnd this is the last line. Please note that this output does not contain the line “This Line Has All Its First Character Of The Word With Upper Case”, even though “is” is there in the “This”, as the following is looking only for the word “is” and not for “this”. The following example is the WORD grep where it is searching only for the word “is”. When you search for “is”, without any option it will show out “is”, “his”, “this” and everything which has the substring “is”. The following example is the regular grep where it is searching for “is”. Just doing out a normal search will show out all the lines. If you want to search for a word, and to avoid it to match the substrings use -w option.

#Grab grep pattern after a symbol full

Checking for full words, not for sub-strings using grep -w

The preceding item is matched at least n times, but not more than m times.ĥ.

+ The preceding item will be matched one or more times.

* The preceding item will be matched zero or more times.

? The preceding item is optional and matched at most once.

$ grep "lines.*empty" demo_fileįrom documentation of grep: A regular expression may be followed by one of several repetition operators: i.e To search “linesempty” in the demo_file. In the following example, it searches for all the pattern that starts with “lines” and ends with “empty” with anything in-between. This is a very powerful feature, if you can use use regular expression effectively. Match regular expression in files Syntax: So it matches all the words such as “the”, “THE” and “The” case insensitively as shown below.Īnd this is the last line. This searches for the given string/pattern case insensitively. Case insensitive search using grep -i Syntax: $ cp demo_file demo_file1ĭemo_file:this line is the 1st lower case line in this file.ĭemo_file:Two lines above this line is empty.ĭemo_file1:this line is the 1st lower case line in this file.ĭemo_file1:Two lines above this line is empty.ĭemo_file1:And this is the last line. When the Linux shell sees the meta character, it does the expansion and gives all the files as input to grep. The grep output will also include the file name in front of the line that matched the specific pattern as shown below. For this example, let us copy the demo_file to demo_file1. This is also a basic usage of grep command. Checking for the given string in multiple files. The basic usage of grep command is to search for a specific string in the specified file as shown below.

Search for the given string in a single file

This Line Has All Its First Character Of The Word With Upper Case.Īnd this is the last line. This line is the 1st lower case line in this file. THIS LINE IS THE 1ST UPPER CASE LINE IN THIS FILE. In this article let us review 15 practical examples of Linux grep command that will be very useful to both newbies and experts.įirst create the following demo_file that will be used in the examples below to demonstrate grep command. Earlier we discussed 15 practical examples for Linux find command, Linux command line history and mysqladmin command. This is part of the on-going 15 Examples series, where 15 detailed examples will be provided for a specific command or functionality. You should get a grip on the Linux grep command.