How to count no of lines in text file and store the value into a variable using batch script?

There is a much simpler way than all of these other methods.

find /v /c "" filename.ext

Holdover from the legacy MS-DOS days, apparently. More info here: https://devblogs.microsoft.com/oldnewthing/20110825-00/?p=9803

Example use:

adb shell pm list packages | find /v /c ""

If your android device is connected to your PC and you have the android SDK on your path, this prints out the number of apps installed on your device.

You could use the FOR /F loop, to assign the output to a variable.

I use the cmd-variable, so it's not neccessary to escape the pipe or other characters in the cmd-string, as the delayed expansion passes the string "unchanged" to the FOR-Loop.

@echo off
cls
setlocal EnableDelayedExpansion
set "cmd=findstr /R /N "^^" file.txt | find /C ":""

for /f %%a in ('!cmd!') do set number=%%a
echo %number%

Inspired by the previous posts, a shorter way of doing so:

CMD.exe
C:\>FINDSTR /R /N "^.*$" file.txt | FIND /C ":"

The number of lines

Try it. It works in my console.

EDITED:

(the "$" sign removed)

FINDSTR /R /N "^.*" file.txt | FIND /C ":"

$ reduces the number by 1 because it is accepting the first row as Field name and then counting the number of rows.