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 in r 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. For instance, will match any character other than "5".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 Grep Command Examples grep(']', mystring)īrackets can also be used to negate a match with a carat ( ^). As another example, will match the characters / or 0-9. Note that these whole expressions must be used inside brackets for instance, to match a single digit, you can use ] (note the double brackets). For instance, is short for a-z, is short for A-Z, is A-z, is 0-9, and is A-z0-9. R also has several shortcut classes that can be used in brackets. all alphanumeric characters) grep('', mystring) will match 0, 1, 2, 3, or 4, will match any uppercase letter, will match any uppercase or lowercase letter, and will match any letter or number (i.e. It may be useful to indicate character sequences. If you want to match one of several characters, you can wrap those characters in brackets ( ) grep('', mystring) # Error: '\.' is an unrecognized escape in character string starting "'\." you need to double escape regular expression characters.) grep('\.org', tricky) However, R tries to look for escape characters when creating strings, so you actually need to escape the backslash itself (i.e. To match a literal character, you have to escape the string with a backslash ( \). ', mystring)īe careful when trying to match dots! tricky <- c(''My friend is a cyborg') It means "match any character" grep('The number. X|y means look for "x" or "y" grep('5|8', mystring) 'Git SSH tag is personal site is 'path/to/my/file')
#Grep usage in r how to#
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