How to find particular contents in list of files - windows

Question

Please can someone tell how to find particular pattern in list of files.
I use the command:
dir *.txt /b /s >> C:\Users\Amrendra\Downloads\NIT_Testing\fileList.txt
In fileList.txt I have a list of files.
Now I want to find a certain pattern say abc in all the files listed.
So I want each line containing that pattern to be written into a new file.
Please suggest as I am completely new to batch command.
Thanks

Answer 1

I'm not sure if I got you completely right. You've echoed the names of all .txt files from some folder into one text file. Now you want to check it line by line for filenames containing some substring in the file name. Is that correct? If it is, here is the solution:
#ECHO OFF
SET targetFile=C:\Some\Path\SomeTextFile.txt
SET sourceFile=C:\Some\Path\Source.txt
SETLOCAL EnableDelayedExpansion
TYPE NUL>%targetFile%
FOR /F "tokens=*" %%L IN (sourceFile) DO (
SET templine=%%L
SET templine=!templine:abc=!
IF NOT !templine!==%%L (
ECHO %%L>>%targetFile%
)
)
Let's take a look on how it works: first we put the path to the file containing the file names into the variable %sourceFile% and the path to the target file into the variable %targetFile%. We need EnableDelayedExpansion to be able to work with changing variables inside the FOR-loop. TYPE NUL>%targetFile% simply clears the target file in case there are some entries from former runs.
The main work is done inside the FOR-loop. We read the source file line by line and want to check if the line contains the substring we are looking for. To do this we first store the line (%%L) in a temporary variable. Then we replace any occurrences of the search string with an empty string, means we simply remove abc from the temporary string. Finally we compare our modified temporary string with the original one. If they are equal we can be sure that the serch string abc was not in the original string. The other way around, if the strings differ, the substring was in the original string. So in the second case we do ECHO %%L>>%targetFile% which means we write the whole file name containing the search substring into our target file. Et voilà, we're done!
EDIT: As you want to search all listed files for the substring, here the new code:
#ECHO OFF
SETLOCAL EnableDelayedExpansion
SET sourceFile=C:\Users\Amrendra\Downloads\NIT_Testing\fileList.txt
SET targetFile=C:\Users\Amrendra\Downloads\NIT_Testing\newList.txt
SET searchString=abc
TYPE NUL>%targetFile%
FOR /F "tokens=*" %%L IN (%sourceFile%) DO (
FINDSTR %searchString% "%%L">NUL
IF !ERRORLEVEL!==0 ECHO %%L>>%targetFile%
)
Here we are using findstr to check if a text file contains the string we are searching. As findstr usually would output the line which contains the searched string (which we don't want) we simply mute the command using >NUL. What we actually need is the ERRORLEVEL! If the string was found in a file findstr will set ERRORLEVEL to 0 or to 1 otherwise. So the only thing we have to do is to check if !ERRORLEVEL!==0.