#GREP USAGE SAMPLE INSTALL#
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If you would like to search for a string in the current directory along with all of the subdirectories, you can specify the –r option to search recursively: # grep –r “function” * 9. Search a string Recursively in all Directories It displays the line number in the file of the given search string: # grep –n “main” setup.py 8. The –n option for grep is very useful when debugging files during compile errors. Similar to piping a grep string to word count ( wc program) grep’s built-in option can perform the same for you: # ifconfig | grep –c inet6 7. The grep’s –C option is similar, but instead of printing the lines that come either before or after the string, it prints the lines in either direction: # ifconfig | grep –C 2 lo 6. While the man page gives a more detailed explanation, I find it easiest to remember the options as –A = after, and –B = before: # ifconfig | grep –A 4 eth0 Display Number of Lines Before or After Search StringĪnother couple of options are the –A and –B switches, which displays the matched line and number of lines either that come before or after the search string. 35 Practical Examples of Linux Find CommandĤ.In this example, we are using find to print all of the files with a *.mp3 extension, piping it to grep –i to filter out and prints all files with the name “ JayZ” and then another pipe to grep –vi which filters out and does not print all filenames with the string (in any case) “ remix”. –name “*.mp3” | grep –i JayZ | grep –vi “remix”

Using a find command with a couple of grep pipes will do the trick: # find. You want to find all of the *.mp3 files from the artist JayZ, but you don’t want any of the remixed tracks.

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For example, let’s say that you have an entire folder full of music files in a bunch of different formats. The grep can be very useful for filtering from stdout. The –v option tells grep to invert its output, meaning that instead of printing matching lines, do the opposite and print all of the lines that don’t match the expression, in this case, the # commented lines. Wouldn’t it be easier for you, the guy helping you, and everyone reading it, if you could remove all of the commented lines? Well you can! Just run this: # grep –v “#” /etc/apache2/sites-available/default-ssl

The kind soul who replies to you has asked you to post the contents of your /etc/apache2/sites-available/default-ssl file. You are having some trouble with your Apache Web Server, and you have reached out to one of the many awesome forums on the net asking for some help. The grep can also be used to search and filter within individual files or multiple files. Using the –i option is a good habit of getting into, unless of course you are trying to nail down a more specific search. Second, we piped that output to grep –i python, which simple states “go to grep and filter out and return everything with ‘python’ in it.” The –i option is there to ignore-case, as grep is case-sensitive. Ii python-pam 0.4.2-12.2ubuntu4 A Python interface to the PAM libraryįirst, we ran dpkg –l, which lists installed *.deb packages on your system. Ii python-openssl 0.12-1ubuntu2.1 Python wrapper around the OpenSSL library Ii python2.7-minimal 2.7.3-0ubuntu3.4 Minimal subset of the Python language (version 2.7) Simply run this command: # dpkg –l | grep –i python Sample Output ii python2.7 2.7.3-0ubuntu3.4 Interactive high-level object-oriented language (version 2.7) You have been scouring the web looking for tutorials, but you see that there are two different versions of Python in use, and you don’t know which one was installed on your system by the Ubuntu installer, or if it installed any modules. Let’s say that you have just installed a fresh copy of the new Ubuntu on your machine, and that you are going to give Python scripting a shot.

I have found that the easiest way to get your feet wet with grep is to just dive right in and use some real world examples.

#GREP USAGE SAMPLE INSTALL#

$ sudo apt-get install grep #Debian/Ubuntu $ sudo yum install grep #RHEL/CentOS/Fedora If, for whatever reason, it is not installed on your system, you can easily install it via your package manager ( apt-get on Debian/ Ubuntu and yum on RHEL/ CentOS/ Fedora). Grep is a powerful file pattern searcher that comes equipped on every distribution of Linux. Have you ever been confronted with the task of looking for a particular string or pattern in a file, yet have no idea where to start looking? Well then, here is grep to the rescue! 12 Practical Examples of Linux grep Command

Grep usage sample