How to search and replace using grep - linux

I need to recursively search for a specified string within all files and subdirectories within a directory and replace this string with another string.
I know that the command to find it might look like this:
grep 'string_to_find' -r ./*
But how can I replace every instance of string_to_find with another string?

Another option is to use find and then pass it through sed.
find /path/to/files -type f -exec sed -i 's/oldstring/new string/g' {} \;

I got the answer.
grep -rl matchstring somedir/ | xargs sed -i 's/string1/string2/g'

You could even do it like this:
Example
grep -rl 'windows' ./ | xargs sed -i 's/windows/linux/g'
This will search for the string 'windows' in all files relative to the current directory and replace 'windows' with 'linux' for each occurrence of the string in each file.

This works best for me on OS X:
grep -r -l 'searchtext' . | sort | uniq | xargs perl -e "s/matchtext/replacetext/" -pi
Source: http://www.praj.com.au/post/23691181208/grep-replace-text-string-in-files

Usually not with grep, but rather with sed -i 's/string_to_find/another_string/g' or perl -i.bak -pe 's/string_to_find/another_string/g'.

Other solutions mix regex syntaxes. To use perl/PCRE patterns for both search and replace, and process only matching files, this works quite well:
grep -rlIZPi 'match1' | xargs -0r perl -pi -e 's/match2/replace/gi;'
match1 and match2 are usually identical but match2 can contain more advanced features that are only relevant to the substitution, e.g. capturing groups.
Translation: grep recursively and list matching filenames, each separated by null to protect any special characters; pipe any filenames to xargs which is expecting a null-separated list; if any filenames are received, pass them to perl to perform the actual substitutions.
For case-sensitive matching, drop the i flag from grep and the i pattern modifier from the s/// expression, but not the i flag from perl itself. To include binary files, remove the I flag from grep.

Be very careful when using find and sed in a git repo! If you don't exclude the binary files you can end up with this error:
error: bad index file sha1 signature
fatal: index file corrupt
To solve this error you need to revert the sed by replacing your new_string with your old_string. This will revert your replaced strings, so you will be back to the beginning of the problem.
The correct way to search for a string and replace it is to skip find and use grep instead in order to ignore the binary files:
sed -ri -e "s/old_string/new_string/g" $(grep -Elr --binary-files=without-match "old_string" "/files_dir")
Credits for #hobs

Here is what I would do:
find /path/to/dir -type f -iname "*filename*" -print0 | xargs -0 sed -i '/searchstring/s/old/new/g'
this will look for all files containing filename in the file's name under the /path/to/dir, than for every file found, search for the line with searchstring and replace old with new.
Though if you want to omit looking for a specific file with a filename string in the file's name, than simply do:
find /path/to/dir -type f -print0 | xargs -0 sed -i '/searchstring/s/old/new/g'
This will do the same thing above, but to all files found under /path/to/dir.

Modern rust tools can be used to do this job.
For example to replace in all (non ignored) files "oldstring" and "oldString" with "newstring" and "newString" respectively you can :
Use fd and sd
fd -tf -x sd 'old([Ss]tring)' 'new$1' {}
Use ned
ned -R -p 'old([Ss]tring)' -r 'new$1' .
Use ruplacer
ruplacer --go 'old([Ss]tring)' 'new$1' .
Ignored files
To include ignored (by .gitignore) and hidden files you have to specify it :
use -IH for fd,
use --ignored --hiddenfor ruplacer.

Another option would be to just use perl with globstar.
Enabling shopt -s globstar in your .bashrc (or wherever) allows the ** glob pattern to match all sub-directories and files recursively.
Thus using perl -pXe 's/SEARCH/REPLACE/g' -i ** will recursively
replace SEARCH with REPLACE.
The -X flag tells perl to "disable all warnings" - which means that
it won't complain about directories.
The globstar also allows you to do things like sed -i 's/SEARCH/REPLACE/g' **/*.ext if you wanted to replace SEARCH with REPLACE in all child files with the extension .ext.

Related

Using "grep" to search for specific type of files in all subdirectories

I am trying to find a specific line in files that contains "Mutual_Values_23.0" in a directory that contains a lot of subdirectories. I know this line number is stored in a file which starts with "gnuout_mutual_....txt" (the ellipses part of the file name is the time stamp so that varies).
I wanted to know if there is a way to specify "grep" command to look into the subdirectories only for the files starting with "gnuout_mutual_....txt"
I have tried
grep -r "Mutual_Values_23.0" *
but that's taking a long time
You can use the following option of grep:
--include=GLOB
Search only files whose base name matches GLOB (using wildcard matching as described under --exclude).
And for the line number you should use the -n option.
From within the root of the folders you want to look into, you can use this final command:
grep -nr "Mutual_Values_23.0" --include="gnuout_mutual_*txt"
Use find to search all sub-directories for the "gnuout...txt` file with the search string "Mutual_Values_23.0"
find . -mindepth 1 -name gnuout_mutual_\*.txt -type f -exec grep "Mutual_Values_23.0" {} +
If you make use of bash, you can use the globstar option:
globstar
If set, the pattern ** used in a pathname expansion context will
match all files and zero or more directories and subdirectories.
If the pattern is followed by a /, only directories and
subdirectories match.
So you can use it like:
$ shopt -s globstar
$ grep "search_string" **/glob-pattern
or in the case of the OP:
$ shopt -s globstar
$ grep Mutual_Values_23.0 **/gnuout_mutual_*.txt
GNU grep has the --include GLOB option where GLOB can be used to specify the file name pattern that you need to match.
grep -rn --include 'gnuout_mutual_*txt' 'Mutual_Values_23.0' .
You could use find to search for files and pass results to grep.
find /directory_where_to_search/ -iname 'gnuout_mutual_*.txt' | xargs grep 'Mutual_Values_23.0' -sl
Use this command:
$ find . -name "*Mutual_Values_23.0*"
Note: Run this command in the directory where you want to search your set of files.
Hope it helps, cheers!

linux : listing files that contain several words

I try to find a way to list all the files in the directory tree (recursively) that contain several words.
While searching I found example such as egrep -R -l 'toto|tata' . but | induce OR. I would like AND...
Thank you for your help
Using GNU grep with GNU xargs,
grep -ERl 'toto' | xargs -r grep 'tata'
The first grep lists those files containing the pattern toto which is then fed to xargs and with the second grep those files containing tata is retrieved. The -r flag is to ensure second grep doesn't run on an empty output.
The -r flag in xargs from the man page,
-r, --no-run-if-empty
If the standard input does not contain any nonblanks, do not run the command.
Normally, the command is run once even if there is no input. This option is a GNU
extension.
agrep tool is designed for providing AND to grep with usage:
agrep 'pattern1;pattern2' file
In your case you could run
find . -type f -exec agrep 'toto;tata' {} \; #apply -l to display the file names
PS1: For current directory you can just agrep 'pattern1;pattern2' *.*
PS2: Unfortunatelly agrep does not support -R option.

Remove files not containing a specific string

I want to find the files not containing a specific string (in a directory and its sub-directories) and remove those files. How I can do this?
The following will work:
find . -type f -print0 | xargs --null grep -Z -L 'my string' | xargs --null rm
This will firstly use find to print the names of all the files in the current directory and any subdirectories. These names are printed with a null terminator rather than the usual newline separator (try piping the output to od -c to see the effect of the -print0 argument.
Then the --null parameter to xargs tells it to accept null-terminated inputs. xargs will then call grep on a list of filenames.
The -Z argument to grep works like the -print0 argument to find, so grep will print out its results null-terminated (which is why the final call to xargs needs a --null option too). The -L argument to grep causes grep to print the filenames of those files on its command line (that xargs has added) which don't match the regular expression:
my string
If you want simple matching without regular expression magic then add the -F option. If you want more powerful regular expressions then give a -E argument. It's a good habit to use single quotes rather than double quotes as this protects you against any shell magic being applied to the string (such as variable substitution)
Finally you call xargs again to get rid of all the files that you've found with the previous calls.
The problem with calling grep directly from the find command with the -exec argument is that grep then gets invoked once per file rather than once for a whole batch of files as xargs does. This is much faster if you have lots of files. Also don't be tempted to do stuff like:
rm $(some command that produces lots of filenames)
It's always better to pass it to xargs as this knows the maximum command-line limits and will call rm multiple times each time with as many arguments as it can.
Note that this solution would have been simpler without the need to cope with files containing white space and new lines.
Alternatively
grep -r -L -Z 'my string' . | xargs --null rm
will work too (and is shorter). The -r argument to grep causes it to read all files in the directory and recursively descend into any subdirectories). Use the find ... approach if you want to do some other tests on the files as well (such as age or permissions).
Note that any of the single letter arguments, with a single dash introducer, can be grouped together (for instance as -rLZ). But note also that find does not use the same conventions and has multi-letter arguments introduced with a single dash. This is for historical reasons and hasn't ever been fixed because it would have broken too many scripts.
GNU grep and bash.
grep -rLZ "$str" . | while IFS= read -rd '' x; do rm "$x"; done
Use a find solution if portability is needed. This is slightly faster.
EDIT: This is how you SHOULD NOT do this! Reason is given here. Thanks to #ormaaj for pointing it out!
find . -type f | grep -v "exclude string" | xargs rm
Note: grep pattern will match against full file path from current directory (see find . -type f output)
One possibility is
find . -type f '!' -exec grep -q "my string" {} \; -exec echo rm {} \;
You can remove the echo if the output of this preview looks correct.
The equivalent with -delete is
find . -type f '!' -exec grep -q "user_id" {} \; -delete
but then you don't get the nice preview option.
To remove files not containing a specific string:
Bash:
To use them, enable the extglob shell option as follows:
shopt -s extglob
And just remove all files that don't have the string "fix":
rm !(*fix*)
If you want to don't delete all the files that don't have the names "fix" and "class":
rm !(*fix*|*class*)
Zsh:
To use them, enable the extended glob zsh shell option as follows:
setopt extended_glob
Remove all files that don't have the string, in this example "fix":
rm -- ^*fix*
If you want to don't delete all the files that don't have the names "fix" and "class":
rm -- ^(*fix*|*class*)
It's possible to use it for extensions, you only need to change the regex: (.zip) , (.doc), etc.
Here are the sources:
https://www.tecmint.com/delete-all-files-in-directory-except-one-few-file-extensions/
https://codeday.me/es/qa/20190819/1296122.html
I can think of a few ways to approach this. Here's one: find and grep to generate a list of files with no match, and then xargs rm them.
find yourdir -type f -exec grep -F -L 'yourstring' '{}' + | xargs -d '\n' rm
This assumes GNU tools (grep -L and xargs -d are non-portable) and of course no filenames with newlines in them. It has the advantage of not running grep and rm once per file, so it'll be reasonably fast. I recommend testing it with "echo" in place of "rm" just to make sure it picks the right files before you unleash the destruction.
This worked for me, you can remove the -f if you're okay with deleting directories.
myString="keepThis"
for x in `find ./`
do if [[ -f $x && ! $x =~ $myString ]]
then rm $x
fi
done
Another solution (although not as fast). The top solution didn't work in my case because the string I needed to use in place of 'my string' has special characters.
find -type f ! -name "*my string*" -exec rm {} \; -print

Replace a string with another string in all files below my current dir

How do I replace every occurrence of a string with another string below my current directory?
Example: I want to replace every occurrence of www.fubar.com with www.fubar.ftw.com in every file under my current directory.
From research so far I have come up with
sed -i 's/www.fubar.com/www.fubar.ftw.com/g' *.php
You're on the right track, use find to locate the files, then sed to edit them, for example:
find . -name '*.php' -exec sed -i -e 's/www.fubar.com/www.fubar.ftw.com/g' {} \;
Notes
The . means current directory - i.e. in this case, search in and below the current directory.
For some versions of sed you need to specify an extension for the -i option, which is used for backup files.
The -exec option is followed by the command to be applied to the files found, and is terminated by a semicolon, which must be escaped, otherwise the shell consumes it before it is passed to find.
Solution using find, args and sed:
find . -name '*.php' -print0 | xargs -0 sed -i 's/www.fubar.com/www.fubar.ftw.com/g'
A pure bash solution
#!/bin/bash
shopt -s nullglob
for file in *.php
do
while read -r line
do
echo "${line/www.fubar.com/www.fubar.ftw.com}"
done < "$file" > tempo && mv tempo "$file"
done
A more efficient * alternative to the currently accepted solution:
`grep "www.fubar.com" . -lr | xargs sed -i 's/www.fubar.com/www.fubar.ftw.com/g'
This avoids the inefficiency of the find . -exec method, which needlessly runs a sed in-place replacement over all files below your current directory regardless of if they contain the string you're looking for or not, by instead using grep -lr. This gets just the files containing the string you want to replace which you can then pipe to xargs sed -i to perform the in-place replacement on just those files.
* : I used time to make a cursory comparison of my method with the accepted solution (adapted for my own use case); The find . -exec-style method took 3.624s to run on my machine and my above proposed solution took 0.156s, so roughly 23x faster for my use case.
If there are no subfolders, a simpler to remember way is
replace "www.fubar.com" "www.fubar.ftw.com" -- *
where * can also be a list of files
from the manual:
Invoke replace in one of the following ways:
shell> replace from to [from to] ... -- file_name [file_name] ...
shell> replace from to [from to] ... < file_name
If you have hidden files with a dot you can add those to * with
shopt -s dotglob
If you only have one depth of subfolders you can use */* instead of *
replace "www.fubar.com" "www.fubar.ftw.com" -- */*
When using ZSH as your shell you can do:
sed -i 's/www.fubar.com/www.fubar.ftw.com/g' **/*.php

How can I use grep to find a word inside a folder?

In Windows, I would have done a search for finding a word inside a folder. Similarly, I want to know if a specific word occurs inside a directory containing many sub-directories and files. My searches for grep syntax shows I must specify the filename, i.e. grep string filename.
Now, I do not know the filename, so what do I do?
A friend suggested to do grep -nr string, but I don't know what this means and I got no results with it (there is no response until I issue a Ctrl + C).
grep -nr 'yourString*' .
The dot at the end searches the current directory. Meaning for each parameter:
-n Show relative line number in the file
'yourString*' String for search, followed by a wildcard character
-r Recursively search subdirectories listed
. Directory for search (current directory)
grep -nr 'MobileAppSer*' . (Would find MobileAppServlet.java or MobileAppServlet.class or MobileAppServlet.txt; 'MobileAppASer*.*' is another way to do the same thing.)
To check more parameters use man grep command.
grep -nr string my_directory
Additional notes: this satisfies the syntax grep [options] string filename because in Unix-like systems, a directory is a kind of file (there is a term "regular file" to specifically refer to entities that are called just "files" in Windows).
grep -nr string reads the content to search from the standard input, that is why it just waits there for input from you, and stops doing so when you press ^C (it would stop on ^D as well, which is the key combination for end-of-file).
GREP: Global Regular Expression Print/Parser/Processor/Program.
You can use this to search the current directory.
You can specify -R for "recursive", which means the program searches in all subfolders, and their subfolders, and their subfolder's subfolders, etc.
grep -R "your word" .
-n will print the line number, where it matched in the file.
-i will search case-insensitive (capital/non-capital letters).
grep -inR "your regex pattern" .
There's also:
find directory_name -type f -print0 | xargs -0 grep -li word
but that might be a bit much for a beginner.
find is a general purpose directory walker/lister, -type f means "look for plain files rather than directories and named pipes and what have you", -print0 means "print them on the standard output using null characters as delimiters". The output from find is sent to xargs -0 and that grabs its standard input in chunks (to avoid command line length limitations) using null characters as a record separator (rather than the standard newline) and then applies grep -li word to each set of files. On the grep, -l means "list the files that match" and -i means "case insensitive"; you can usually combine single character options so you'll see -li more often than -l -i.
If you don't use -print0 and -0 then you'll run into problems with file names that contain spaces so using them is a good habit.
grep -nr search_string search_dir
will do a RECURSIVE (meaning the directory and all it's sub-directories) search for the search_string. (as correctly answered by usta).
The reason you were not getting any anwers with your friend's suggestion of:
grep -nr string
is because no directory was specified. If you are in the directory that you want to do the search in, you have to do the following:
grep -nr string .
It is important to include the '.' character, as this tells grep to search THIS directory.
Why not do a recursive search to find all instances in sub directories:
grep -r 'text' *
This works like a charm.
Similar to the answer posted by #eLRuLL, an easier way to specify a search that respects word boundaries is to use the -w option:
grep -wnr "yourString" .
Another option that I like to use:
find folder_name -type f -exec grep your_text {} \;
-type f returns you only files and not folders
-exec and {} runs the grep on the files that were found in the search (the exact syntax is "-exec command {}").
grep -r "yourstring" *
Will find "yourstring" in any files and folders
Now if you want to look for two different strings at the same time you can always use option E and add words for the search. example after the break
grep -rE "yourstring|yourotherstring|$" * will search for list locations where yourstring or yourotherstring matches
The answer you selected is fine, and it works, but it isn't the correct way to do it, because:
grep -nr yourString* .
This actually searches the string "yourStrin" and "g" 0 or many times.
So the proper way to do it is:
grep -nr \w*yourString\w* .
This command searches the string with any character before and after on the current folder.
grep -R "string" /directory/
-R follows also symlinks when -r does not.
The following sample looks recursively for your search string in the *.xml and *.js files located somewhere inside the folders path1, path2 and path3.
grep -r --include=*.xml --include=*.js "your search string" path1 path2 path3
So you can search in a subset of the files for many directories, just providing the paths at the end.
Run(terminal) the following command inside the directory. It will recursively check inside subdirectories too.
grep -r 'your string goes here' *
Don't use grep. Download Silver Searcher or ripgrep. They're both outstanding, and way faster than grep or ack with tons of options.

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