linux find word in file not in another file

Linux find word in file not in another file how to#
Linux find word in file not in another file full#

If you run the same command as above, including the -w option, the grep command will return only those lines where gnu is included as a separate word. All other characters are considered as non-word characters. Word characters include alphanumeric characters ( a-z, A-Z, and 0-9) and underscores ( _). To return only those lines where the specified string is a whole word (enclosed by non-word characters), use the -w ( or -word-regexp) option. When searching for a string, grep will display all lines where the string is embedded in larger strings.įor example, if you search for “gnu”, all lines where “gnu” is embedded in larger words, such as “cygnus” or “magnum” will be matched: grep gnu /usr/share/words cygnus Specifying “Zebra” will match “zebra”, “ZEbrA” or any other combination of upper and lower case letters for that string. To ignore case when searching, invoke grep with the -i option (or -ignore-case).įor example, when searching for Zebra without any option, the following command will not show any output i.e there are matching lines: grep Zebra /usr/share/wordsīut if you perform a case insensitive search using the -i option, it will match both upper and lower case letters: grep -i Zebra /usr/share/words This means that the uppercase and lowercase characters are treated as distinct. The -l option is usually used in combination with the recursive option -R: grep -Rl /tmp Case Insensitive Search #īy default, grep is case sensitive. The output will look something like this: nf

conf in the current working directoryĪnd prints only the names of the files containing the string : grep -l *.conf The command below searches through all files ending with.

To suppress the default grep output and print only the names of files containing the matched pattern, use the -l ( or -files-with-matches) option. etc/nginx/sites-available/: server_name /etc/nginx/sites-enabled/: server_name Show Only the Filename # That line is not printed when grep is invoked with -rbecause files inside the Nginx’s sites-enabled directory are symlinks to configuration files inside the sites-available directory. Notice the last line of the output below. etc/nginx/sites-available/: server_name If you use the -R option, grep will follow all symbolic links: grep -R /etc

Linux find word in file not in another file full#

The output will include matching lines prefixed by the full path to the file:

Linux find word in file not in another file how to#

Here is an example showing how to search for the string in all files inside the /etc directory: grep -r /etc , instead of -r, use the -R option (or -dereference-recursive). When this option is used grep will search through all files in the specified directory, skipping the symlinks that are encountered recursively. To recursively search for a pattern, invoke grep with the -r option (or -recursive). If you don’t want that line to be shown pass the output to another grep instance as shown below. As you can see in the output above there is also a line containing the grep process. You can also chain multiple pipes in on command. Using Grep to Filter the Output of a Command #Ī command’s output can be filtered with grep through piping, and only the lines matching a given pattern will be printed on the terminal.įor example, to find out which processes are running on your system as user www-data you can use the following psĬommand: ps -ef | grep www-data www-data 18247 12675 4 16:00 ? 00:00:00 php-fpm: pool www To display the lines that do not match a pattern, use the -v ( or -invert-match) option.įor example, to print the lines that do not contain the string nologin you would use: grep -v nologin /etc/passwd root:x:0:0:root:/root:/bin/bashĬolord:x:124:124::/var/lib/colord:/bin/false If the string includes spaces, you need to enclose it in single or double quotation marks: grep 'Gnome Display Manager' /etc/passwd Invert Match (Exclude) # The output should look something like this: root:x:0:0:root:/root:/bin/bash The most basic usage of the grep command is to search for a string (text) in a file.įor example, to display all the lines containing the string bash from the /etc/passwdįile, you would run the following command: grep bash /etc/passwd To be able to search the file, the user running the command must have read access to the file. The items in square brackets are optional.