ngrep – grep applied to the network layer.pgrep – searches running processes and lists the process IDs which match the selection criteria to stdout.
find – Find files or directories under the given directory tree recursively. To display lines with 3 w’s in a row (www), use: grep -E 'w' filename To display the lines starting with ‘er’, use: grep -e '^er' filename To return all lines which don’t match the pattern, use: grep -v 'warning' /var/log/nginx/error.log To display the line number of the matching pattern, use: grep -n 'pattern' filename To display the matching part of the pattern, use: grep -o 'pattern' filename To display x lines around the matching pattern, use: grep -C x 'pattern' filename To display x lines before the matching pattern, use: grep -B x 'pattern' filename To display x lines after matching pattern, use: grep -A x 'pattern' filename To display the filename which contains the pattern, use: grep -l 'pattern' /var/log/* Grep was originally developed for the Unix operating system but eventually made available for all Unix-like systems, such as Linux. To perform a case insensitive (ignore case) search, use: grep -i 'pattern' filename To search for a whole word, not a part of a word, use: grep -w 'word' /path/to/file To search directories recursively, use: grep -r 'hello' /path/to/dir To search for an exact pattern, use: grep -F "pattern" /path/to/file To search all files in the current directory, use: grep pattern * To search for a pattern within a file, use: grep "pattern" /path/to/file The general syntax of the grep command is: grep grep was originally developed for the Unix operating system but eventually made available for all Unix-like systems, such as Linux. When it finds a match in a line, grep then copies the line to standard output or whatever output you have selected using options. Following picture show the example for the line numbers.Grep ( global regular expression printer) searches through a file for a specific pattern of characters. This will help user to go the line when user open the file in vi editer to know nearby logs. grep display with Line numbers: grep with option -n print the line number where the search text is present. Following picture show the example where we can see error (small letter) appeared two time in the log file an Error (with captil ‘E’) appeared 22 time in the event-log file. count option is case sensitive, be sure about the actual search string. This is useful when we want to know how many time one particular error happen in the log file. grep with count: grep with option -c search and provide the number of count for a text or string appeared in the file. Grep command can also be combined with other commands with the use of the pipe operator. For example if you want to search error in a file, you can put error or Error in search text will ingore and provide all related matching lines. We use grep command to search within files or output of text. 
grep with ingore case: grep with option -i search for the given text and igore the upper/lower case.-o : Print only the matched parts of a matching line, with each such part on a separate output line.-E : Treats pattern as an extended regular expression.-f file : Takes patterns from file, one per line.Its name comes from the ed command g/re/p (globally. -e exp : Specifies expression with this option. grep is a command-line utility for searching plain-text data sets for lines that match a regular expression.-v : This prints out all the lines that do not matches the pattern.-n : Display the matched lines and their line numbers.-i : Ignores upper/lower case for matching.-h : Display the matched lines, but do not display the filenames.-c : This prints a count of the lines that match the pattern.
#Grep command linux windows#
grep does not work in the Windows environment. grep user requires read/write permissions to access the desired files and directories. grep requires access to a terminal/command line. egrep, and fgrep are other similar tools. The grep command is handy tool for searching known text or string through large log files. When grep finds a match, it prints the line with the result. grep stands for global regular expression and print May 21, 2022Knowledge grep options expression filename Syntax : grep string file Syntax : grep string /path/to/ Syntax : grep -color string. In this blog posts, Let us dicuss what are different ways we can used grep on a Linux system. It is one of the most useful commands on Linux systems for Developers and testers for debugging the system logs. In other words, we can say that grep command search provides the lines containing a match strings or words in the given file. Grep is an essential command utility used in Linux and Unix environments to search text and strings in a given file.
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