how get the same keyword in file - batch-file

Question

I have a list file
MFC_530_18MM_007_F0
MFC_520_18MM_008_F0
MFC_430_18MM_001_F1
MFC_270_18MM_002_F1
MFC_270_18MM_003_F1
MFC_720_18MM_004_F1
MFC_130_18MM_005_F1
MFC_540_18MM_006_F1
MFC_BT580_18MM_007_F1
MFC_530_18MM_008_F1
MFC_MP110_18MM_009_F1
MFC_AAC1_18MM_010_F1
I want to get the same name
ex:
MFC_530_18MM
MFC_520_18MM
MFC_430_18MM
MFC_270_18MM
MFC_270_18MM
MFC_720_18MM
MFC_130_18MM
MFC_540_18MM
MFC_BT580_18MM
MFC_530_18MM
MFC_MP110_18MM
MFC_AAC1_18MM
I have this code:
#echo off
set "R_Str_f=_0.*"
set "R_Str_fed="
setlocal enableDelayedExpansion
(
for /f "tokens=1* delims=:" %%a in ('findstr /n "^" source.txt') do (
set "line=%%b"
if defined line set "line=!line:%R_Str_f%=%R_Str_fed%!"
echo(!line!
)
)> output.txt
I want this code to remove the last character and then remove duplicate keywords but it does not work

Answer 1

not sure which OS you're using.
on Unix/Linux and SHELL you can try to use the "_" as a field separator (FS)
cat yourfile | awk 'FS="_" { print $1"_"$2"_"$3}'

Answer 2

If the requirement is to result in the first three (3) items separated by LOW LINE (underscore) characters, this might work.
#powershell -NoLogo -NoProfile -Command ^
"Get-Content -Path '.\in.txt' | ForEach-Object {($_ -split '_')[0..2] -join '_'}"
Result:
PS C:\src\t\so68080140> .\doit.bat
MFC_530_18MM
MFC_520_18MM
MFC_430_18MM
MFC_270_18MM
MFC_270_18MM
MFC_720_18MM
MFC_130_18MM
MFC_540_18MM
MFC_BT580_18MM
MFC_530_18MM
MFC_MP110_18MM
MFC_AAC1_18MM

Answer 3

Given that your question intent appears to be to replace everything from and including _0 with nothing, does this help?
#Echo Off
SetLocal EnableExtensions DisableDelayedExpansion
( For /F UseBackQ^ Delims^=^ EOL^= %%G In ("source.txt") Do (
Set "LineContent=%%G"
SetLocal EnableDelayedExpansion
For /F UseBackQ^ EOL^=^|^ Delims^=^| %%H In (
'!LineContent:_0^=^|!'
) Do EndLocal & Echo(%%H
)
) 1>"output.txt"
For the above example code to work, I have assumed, and therefore it is a requirement, that your initial strings do not include any | characters.
If you are using Windows 10, and do not mind what order your output file list is in, then you could probably perform the entire task, i.e. with duplicates removed, like this:
#Echo Off
SetLocal EnableExtensions
(
For /F UseBackQ^^^ Delims^^^=^^^ EOL^^^= %%G In ("source.txt") Do #(
Set "LineContent=%%G"
%SystemRoot%\System32\cmd.exe /D /C "Echo(%%LineContent:_0=&:%%"
)
) | %SystemRoot%\System32\sort.exe /Unique 1>"output.txt"