Find string from file linux

grep «Serializable» -rl . —exclude=*.

Find string recursively all files including some extensions and excluding others

grep string -r . —include=*.myextension —exclude=*.myextension2

grep «my=string» -r . —include=*. —exclude=*.js

*It won’t look for the string in the js files.

Find string recursively in only some specific files and show their filename

grep string -rl . —include=*.myextension

grep «name=Oscar» -rl . —include=*.js

Find files and find a string in them using find

find . -name ‘*.extension’ -exec grep string +

find . -name ‘*.txt’ -exec grep Mytext <> +

find . -type f \( -name ‘*.htm’ -or -name ‘*.html’ \) -exec grep -i «mystring» <> +

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Finding a File Containing a Particular Text String In Linux Server

You need to use the grep command. The grep command or egrep command searches the given input FILEs for lines containing a match or a text string.

grep command syntax for finding a file containing a particular text string

The syntax is:
grep » text string to search » directory-path
grep [option] » text string to search » directory-path
grep -r » text string to search «directory-path
grep -r -H » text string to search » directory-path
egrep -R » word-1|word-2 » /path/to/directory
egrep -w -R » word-1|word-2 » directory-path
Let us see some common example on how to use grep to search for strings in files.

How to search and find all files for a given text string

In this example, search for a string called ‘redeem reward’ in all text (*.txt) files located in /home/tom/ directory, use:
$ grep «redeem reward» /home/tom/*.txt
OR
$ grep «redeem reward»

Task: Search all subdirectories recursively

You can search for a text string all files under each directory, recursively with -r option:
$ grep -r «redeem reward» /home/tom/
OR
$ grep -R «redeem reward» /home/tom/
Look for all files containing cacheRoot text on Linux:
grep -R cacheRoot /home/vivek/

Trying to find all files containing specific text on my Linux desktop

Task: Only display filenames

By default, the grep command prints the matching lines. You can pass -H option to print the filename for each match:
$ grep -H -r «redeem reward» /home/tom
Sample outputs:

To just display the filename use the cut command as follows:
$ grep -H -R vivek /etc/* | cut -d: -f1
Sample outputs:

Task: Suppress file names

The grep command shows output on a separate line, and it is preceded by the name of the file in which it was found in the case of multiple files. You can pass the -h option to suppress inclusion of the file names in the output:
$ grep -h -R ‘main()’

Task: Display only words

You can select only those lines containing matches that form whole words using the -w option. In this example, search for word ‘getMyData()’ only in

/projects/ dirctory:
$ grep -w -R ‘getMyData()’

Task: Search for two or more words

Use the egrep command as follows:
$ egrep -w -R ‘word1|word2’

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Task: Hide warning spam

grep command generate error message as follows due to permission and other issues:

No such file or directory
No such device or address
Permission denied

To hide all errors or warning message spam generated by the grep command, append 2>/dev/null to grep command. This will send and hide unwanted output to /dev/null device:
$ grep -w -R ‘getMyData()’

Task: Display matched text in color

Pass the —color option to the grep command display matched text/words in color on the terminal:

Fig.01: grep command in action with colors and hiding the warnings on screen

Task: Ignore case

Our final example ignore case distinctions in both the search PATTERN and the input files:
grep -i -R ‘word’ /path/to/dir
grep -i -r ‘income tax’

How do I find all files containing specific text on Linux?

The syntax is:
egrep ‘pattern’ -rnw /path/to/dir/
egrep ‘word1|word2’ -rnw /home/vivek/backups/

Finding text strings within files using grep

In this example search for lines starting with any lowercase or uppercase letter:
grep «^[a-zA-Z]» -rns

• -r – Recursive search
• -R – Read all files under each directory, recursively. Follow all symbolic links, unlike -r grep option
• -n – Display line number of each matched line
• -s – Suppress error messages about nonexistent or unreadable files
• -w – Only work on words i.e. search only those lines containing matches that form whole words
• -l – Show the name of each input file when match found
• -i – Ignore case while searching

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Linux find text in files

Posted on February 12, 2016 By Nikola Stojanoski

If you need to find text in file or multiple files on a Linux system you can use grep (global regular expression print) in a very efficient way to do so. Here are few examples that I commonly use.

Find text in files into a directory

Use this command to find the text you are looking for within the directory

If you want to select only those lines containing matches that form whole words use the -w switch (–word-regexp). If you search for “word” this will NOT display words like someword, word123, etc.

If you don’t know the capitalization of words and want to ignore case distinctions use the -i switch (–ignore-case). If you search for “word” it will display Word, WORD, word, wORD, etc.

And the most often used command for me is recursive search -r switch (–recursive)

And finally few examples that i use the most

1. Find text in files recursive

Invoke -w (–word-regexp) and -r (–recursive) switch:

2. Find text in files case insensitive and recursive

Invoke -i (–ignore-case) and -r (–recursive) switch

3. Find multiple words in files

To find two different words you must use egrep

This days i use this to search trough logs, mostly apache, nginx and mail logs.

Also don’t forget to use zgrep. Zgrep invokes grep on compressed or gzipped files. All options specified are passed directly to grep.

For this we will use grep case insensitive because sometimes mail addresses can have Capital letters in the user First and Last Names.

This will output file and date when the mail was sent to the user, and than you can grep the time to get all the logs for that time:

You can now easy look at the log:

This ware just few command i usually use, look at the man page for more options.

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How to use sed to find and replace text in files in Linux / Unix shell

Find and replace text within a file using sed command

The procedure to change the text in files under Linux/Unix using sed:

1. Use Stream EDitor (sed) as follows:
2. sed -i ‘s/old-text/new-text/g’ input.txt
3. The s is the substitute command of sed for find and replace
4. It tells sed to find all occurrences of ‘old-text’ and replace with ‘new-text’ in a file named input.txt
5. Verify that file has been updated:
6. more input.txt

Let us see syntax and usage in details.

Syntax: sed find and replace text

The syntax is:
sed ‘s/word1/word2/g’ input.file
## *bsd/macos sed syntax#
sed ‘s/word1/word2/g’ input.file > output.file
sed -i ‘s/word1/word2/g’ input.file
sed -i -e ‘s/word1/word2/g’ -e ‘s/xx/yy/g’ input.file
## use + separator instead of / ##
sed -i ‘s+regex+new-text+g’ file.txt
The above replace all occurrences of characters in word1 in the pattern space with the corresponding characters from word2.

Examples that use sed to find and replace

Let us create a text file called hello.txt as follows:
$ cat hello.txt
The is a test file created by nixCrft for demo purpose.
foo is good.
Foo is nice.
I love FOO.
I am going to use s/ for substitute the found expression foo with bar as follows:
sed ‘s/foo/bar/g’ hello.txt
Sample outputs:

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Please note that the BSD implementation of sed (FreeBSD/MacOS and co) does NOT support case-insensitive matching. You need to install gnu sed. Run the following command on Apple Mac OS:
$ brew install gnu-sed
######################################
### now use gsed command as follows ##
######################################
$ gsed -i ‘s/foo/bar/g I ‘ hello.txt
$ cat hello.txt

sed command problems

Consider the following text file:
$ cat input.txt
http:// is outdate.
Consider using https:// for all your needs.
Find word ‘http://’ and replace with ‘https://www.cyberciti.biz’:
sed ‘s/ http:// / https://www.cyberciti.biz /g’ input.txt
You will get an error that read as follows:

Our syntax is correct but the / delimiter character is also part of word1 and word2 in above example. Sed command allows you to change the delimiter / to something else. So I am going to use +:
sed ‘s+ http:// + https://www.cyberciti.biz +g’ input.txt
Sample outputs:

How to use sed to match word and perform find and replace

In this example only find word ‘love’ and replace it with ‘sick’ if line content a specific string such as FOO:
sed -i -e ‘/FOO/s/love/sick/’ input.txt
Use cat command to verify new changes:
cat input.txt

Recap and conclusion – Using sed to find and replace text in given files

The general syntax is as follows:
## find word1 and replace with word2 using sed ##
sed -i ‘s/word1/word2/g’ input
## you can change the delimiter to keep syntax simple ##
sed -i ‘s+word1+word2+g’ input
sed -i ‘s_word1_word2_g’ input
## you can add I option to GNU sed to case insensitive search ##
sed -i ‘s/word1/word2/gI’ input
sed -i ‘s_word1_word2_gI’ input

See BSD(used on macOS too) sed or GNU sed man page by typing the following command:
man sed

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How to Find Text in Files in Linux

For a system administrator, working with text files is a common phenomenon. Maybe need to find a specific section from piles of log files for troubleshooting something? Or, need to find the document that contains essential information quickly?

In the case of Linux, there are numerous methods to find texts in files. It’s possible using both built-in tools and 3rd-party apps. Check out how to find texts in files in Linux.

Finding text in files

Depending on the number of files you have to perform a search on, there are two ways to perform the text search: automated or manual. If you have to work with a couple of text files, the manual search is more suitable. However, if there are hundreds of text files, then the automated search is the most efficient.

For automated search, we’ll be using grep. Grep comes pre-installed on any Linux distro. As for manual search, any modern text editor will do the job.

Find text in files using grep

In Linux, grep is the default tool for searching texts. Its name is derived from the ed command g/re/p that stands for “globally search for a regular expression and print matching lines.” It’s available on any modern Linux distro.

Grep is a command-line tool. Its command structure is as follows.

As the name of grep suggests, the pattern to search for is described using a regular expression. The regular expression is a special type of string that describes a pattern to match, locate, and manage. To learn more about grep and regular expression, check out using grep and egrep with regular expression.

For demonstration purposes, grab a sample text file. In this example, download the GNU General Public License v3.0 text file.

Basic search

The fundamental way of using grep is to search for a basic string.

Take a look at the following grep command. It’ll search for the word “GNU” in the text file.

To show the line number, use the “-n” flag.

To perform a case-insensitive search using grep, use the “-i” flag.

You may not want to see the search matches but only the file name where the match happened in some situations. To print only the filename, use the “-l” flag. Here, the asterisk denotes to use all the text files in the current directory.

We can also pipe the output of other commands to grep.

Regular expression

Regex offers a smart way of fine-tuning the search. It has its own rules. However, different applications and programming languages implement regular expression differently. Here are a couple of examples that you can use with grep.

To define that the string is to be found at starting a line, use the caret (^) symbol.

To define that the string is to be found at the end of a line, use the dollar sign ($).

To describe that there can be any character at a certain location of the pattern, use the period character (.). For example, the expression “G.U” is valid if there’s any character between “G” and “U”.

To describe that there can be a subset of characters at a particular location of the pattern, use the brackets ([]). For example, the expression “t[wo]o” tells that the match is valid for “two” and “too” only.

Extended regular expression

As the name suggests, an extended regular expression can do more complex things than basic regular expressions. To use extended regular expression with grep, you have to use the “-E” flag.

To search for two different strings, use the OR operators (|).

Finding text in files

Now comes the main part. Instead of manually telling grep the file to perform the search on, grep can do it automatically. In the following command, grep will use all the available text files in the current directory for searching the pattern.

If you want to grep to perform the search on a different directory, then you have to specify the location.

If there are folders, grep doesn’t explore them by default. To tell grep to search recursively, use the “-R” flag.

Grep GUI

If you prefer to work with GUI but still want to enjoy grep’s features, then check out searchmonkey. It’s a front-end solution for grep. The package is available on almost all the major Linux distros.

Find text in files using nano

GNU Nano is a simple and powerful text editor that comes with any Linux distro. It has built-in features to search for text in a text file.

Note that in this method, you have to open the text file, and search manually. It’s doable if there’s only a handful of text files to work with. If there’s more, then using grep is the most optimal choice.

Open the text file in nano.

To search for a string match, press “Ctrl + W”. After typing the string to search for, press “Enter”.

Find text in files using Vim

Vim is a well-known and reputed text editor. It’s the command-line equivalent of a modern text editor. Vim comes with numerous advanced features like plugins, macros, auto-completion, filters, etc.

Similar to nano, Vim works with a single file at a time. If you have multiple text files, then using grep is the most optimal way to go.

To search in a text file, first, open it in Vim.

Enter the following Vim command and hit “Enter”.

Find text in files using GNOME Text Editor

The GNOME Text Editor is the text editor that comes with the GNOME desktop. It’s a simplistic text editor with all the basic features you’d expect. It’s a nice alternative to the command-line text editors.

Similar to nano and vim, the same caution applies to this method. If the number of text files is large, then you better stick with grep.

Open the text file in Text Editor. Press “Ctrl + F” to bring up the search bar.

Find text in files using VS Code

Visual Studio Code is a powerful text editor with tons of features. It’s optimized for programmers to be used as if it’s a full-fledged IDE. It’s available on almost all the major Linux distros.

Install the Visual Studio Code snap package.

Open the text file in VS Code. Press “Ctrl + F” to start searching.

Final thoughts

There are numerous ways to search text in files. It’s an easy task to master. It’s strongly recommended to master the grep command because it offers the most value in terms of efficiency and ease-of-use.

If you prefer GUI, then there are numerous text editors to choose from. Any modern text editor will provide the text search option.

About the author

Sidratul Muntaha

Student of CSE. I love Linux and playing with tech and gadgets. I use both Ubuntu and Linux Mint.

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