Grep Command:

The grep command, which means a global regular expression print, it remains amongst the most versatile commands in a Linux terminal environment.

String :

A string is a contiguous sequence of values, such as a character string and a binary digit string.         


/b      Matches the pattern for beginning of a line

/c      Matches the pattern at end of the line

/L      Searches a string literally

/r       Searches a string as the regular expression and findstr interpret the metacharacters as the regular unless.

/s       Search for the matching files in the current directory

/i         Specifies the search is not be case sensitive

/x        Prints lines that match exactly

/v        Prints line number that cannot contain the matches

/n        Prints the line number and before each line that matches

/m       Prints the filename and file contain a match

/o        Prints the seek offset before the each matching line

/p        Skips files list with offline attribute details

/offline Process for the offline attribute set

/f.file    Reads the list for the specified file formats.

/c: string uses the specified text and literal search string

/g: file    Gets search strings and specified file.

/d:dirlist Searches a  comma-delimited list of directories details

Grep function:

Grep stands for the global regular expression print and also processes the text line which matches the specified pattern logic.

Related comments

  • Ed
  • Red
  • Red and ed


     ed is an interactive file editor components.

red is a short term for restricted ed. It is a version of ed which carries the restrictions between about what types of editing can be done and the task can be performed.

Technical description:

  1. ed is a line-oriented text editor with a minimal interface resource. It is used to create, display, modify the applications or files and otherwise manipulate text oriented files.
  2. ed is invoked with a filename argument constructor, and then a copy of the file is read into the editor’s buffer components. Changes are made to this copy and not directly send to the file itself. Any changes that are not explicitly saved with a ‘w’ command lose the file components.
  3. Editing can be performed with two distinct modes, command and input applications. When first invoked ed is in command mode applications, ed commands are read from the standard input and executed to manipulate the contents of the editor buffer oriented files applications.
  4. Input command, such as ‘a’ append the text files, insert the ed documents, ed enters input mode. This is the primary means of adding text to a file device. In this mode, no commands are available for that app, instead of that standard input is written directly to the editor buffer applications. Lines consist of text up to and includes a newline character operator.
  5. Another important thing to remember is that all ed commands operate on the whole. For the example, the ‘d’ command remove the lines, and then the m command moves lines various text. and it is possible to modify only a portion of a line by specific replacement files.

Line address:

An address represents the number of lines in the buffer to be loaded and it’s ed maintains a current address which is supplied with the commands as the default address, if none other is specified in the file applications.

When a file is first to read, the current address is set to the last line of the file device. In general, at any given time the current address is set to the last line affected by a command prompt.

And the address as a place marker to the last line in the file where ed has done something file’s are occurred, or otherwise, the line where it will operate next level.

Common Linux commands:


    Lists files and directories that are within your current directory files. This command is similar to the dir command for the Windows. The additional files and directory details add the -al options to be Ls -al

Cd Location:

Navigates the directories. Replace the location with the path for the directory that you navigate it.

Cat filename:

Replace the filename with the relative path to the file that you wish to view content.

Example: Cat filename.txt

Tail filename:

Replace the filename with the relative path and the file that you wish to the viewpoint.

Example: Tail filename.txt

More filename:

Print the contents of the file to the CLI, one on the screen at a time. Replace the filename with the relative path the file that you wish to view the content.

Pico string filename:

Replace the string with a single word, or the multiple words within the single quote (”). And Replace the filename with the relative path to the file that you wish to search the current content.

Example: Pico filename.txt

Grep string filename:

Replace the string with a single word, or the multiple words within single quotes (”). Replace filename with the relative path to the file that you wish to search the content value.

Example: Grep ‘filters’ common list.txt

1. Search for the string in a single file:


Grep  “little_string” filename

$ grep the “this” demo_file

2. Searching for the string for multiple files:


Grep “string” File_pattern types

3. Case insensitive search:


Grep  -i “string that value” file

4. Match regular expression in files:


Grep “REGEX” filedir

And these expression is the powerful feature and that can expression effectively.

5. Checking for the full words and not for substrings using grep-w:

 $ grep -i is demo_file format<>/code<

This line is the 1st upper line for this file and this is the last line.

6. Searching in all files recursively using the grep-r:

The user search for the files under the current directory and its sub directory. -r option can be is the one which you need to use.

$ grep -r “rahul” *

7. Displays the lines that cannot match the given pattern:


Grep -v -e “pattern demo” -e “pattern list”

8. Counting the no of matches the grep-c:

This syntax is used for counting the lines for the matches grep lines.


Grep -v  -e  “pattern limit” -e “pattern data”

9. Show only matched string:

Only the matched strings are pattern then use the -o options.

$ grep -o and “is.*line” demo_file1

Is line

And is the line is the 1st lowercase line.

Is the last line lowercase.

10. Invert the match using grep-v:

The user had different options to show the lines matched, and it shows the lines before the match, and to show the lines after the match the applications, and to highlight match variant and want the option -v to do invert match.

$ grep -v “go” demo_text1

Search string in files in the shell:

Basic Grep commands:

 grep 'byte' filename
 grep 'byte' file1 file2 file3
 grep 'string1 string2'  filename
 cat other directory | grep 'something occur'
 command | grep 'something occur'
 command option1 | grep 'data process application'
 grep --color 'data' fileName directories.

How to use the grep command searching in file directories:

Grep tom/etc/password

Recursive use Grep:

Grep -r “mydomain”/etc/apache2/

Grep invert match:

Users can use v-option to list of files that match.

Grep -v par/path/to/file directories

How to list only the names of matching files:

Grep -1 ‘primary file’ *.c

Finding the file for a text string in Linux server:

Grep command is used for finding the files and it’s used for the command searches.

Grep command syntax details:

Grep “text string to search the directory path


grep “text string to search for the directory path


Grep -r “text string for the search directory path”


Egrep -r “word-1/word2 the string directory string”

And the search for the string called redeem reward” in-call directory

$grep “redeem reward” home/tom/*.text


$grep “redeem reward” /*.text.

Search the file for all directory by using the command 

$ grep -r “redeem reward” /home/tom/text


$ grep -r “redeem reward list” /home/tom/

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