Batch file variable filenames: make timestamp filename within a for loop?

Question

I am trying to run a batch of Lighthouse audits from the command line and output the results to JSON files. To ensure they don't overwrite one another, each file name needs to be unique. I would like to use the timestamp as the filename ideally. I have been through many other Stack questions on a similar topic, but I cannot get this to work. I am currently using the below code, written within a batch file and called from Windows command line:

SETLOCAL ENABLEDELAYEDEXPANSION
for /f "delims=" %%a in (C:\Users\User\Desktop\Folder\Lighthouse_Project\urls.txt) DO (
    set dte=!DATE:/=-%!
    set tme=!TIME::=-%!
    set tme=!%tme:.=-%!
    ECHO Line is: %%a
    lighthouse %%a --quiet --chrome-flags=" --headless" --output=json --output-path=C:\Users\User\Desktop\Folder\Lighthouse_Project\json_logs\!dte!!tme!.json
)

The first file produced has the correct name all subsequent JSONs have the literal name: ',dte.,tme.'. and do overwrite one another, If you run the Lighthouse command outside of a for loop it executes perfectly. I'm aware that variables don't update within a for loop but I thought !var! could be used to counter this. The for loop iterates through a list of URLs stored in urls.txt, auditing each of them in turn and returning a JSON file.

Current outcome: .dte!!tme!.json
Desired oucome: 08-10-201913-55-12-07.json , 08-10-201913-56-14-00.json etc.

If anybody knows how to amend this to achieve the correct outcome I would be very grateful.

The urls.txt contains a list of URLs, each on a new line:

 https://www.bbc.co.uk/weather/2643743 https://www.bbc.com/mundo https://regex101.com/ https://www.bbc.co.uk/news

Answer 1

By keeping the expansion without exiting the loop as you intended.. Note I have added a timeout of millisecond here to ensure we have a different time each time. ping 127.0.0.1 -n 1 -w 500> nul :

@echo off
setlocal enabledelayedexpansion
for /f "delims=" %%a in (%userprofile%\Desktop\Croud_DS_1\Lighthouse_Project\urls.txt) DO (
     set dte=!date:/=-!
     set tme=!time::=-!
     set tme=!tme:.=-!
     set tme=!tme:,=-!
     echo Line is: %%a
     lighthouse "%%a" --quiet --chrome-flags=" --headless" --output=json --output-path=%userprofile%\Desktop\Folder\Lighthouse_Project\json_logs\!dte!_!tme!.json
     ping 127.0.0.1 -n 1 -w 500> nul
)

Please take note, I took the liberty of adding an underscore to make sure the date and time format is readable, so you'll have YYYY-MM-dd_HH-mm-ss-ms

Answer 2

Example:

@Echo Off
SETLOCAL ENABLEDELAYEDEXPANSION
for /f "delims=" %%a in (C:\Users\Owner\Desktop\Folder\Lighthouse_Project\urls.txt) DO (
set dte=!DATE:/=-!
set tme=!TIME::=-!
set tme=!tme:.=-!
ECHO Line is: %%a
echo lighthouse "%%a" --quiet --chrome-flags="--headless" --output=json --output-path="C:\Users\Owner\Desktop\Folder\Lighthouse_Project\json_logs\!dte!!tme!.json"
Timeout 2 >NUL
)
Timeout -1 >NUL

This uses the exact content from your urls.txt example. I have added @Echo Off at the top to reduce screen clutter, and an echo in front of your lighthouse command so that it displays instead of runs. Additionally I included a couple of timeout s to both simulate a short timespan, (as the command is being echo 'ed not ran) , and to give you an opportunity to read the output at the end.

Here's the output from the above to prove my case:

Line is: https://www.bbc.co.uk/weather/2643743
lighthouse "https://www.bbc.co.uk/weather/2643743" --quiet --chrome-flags="--hea
dless" --output=json --output-path="C:\Users\Owner\Desktop\Folder\Lighthouse_Pro
ject\json_logs\08-10-201916-12-42-93.json"
Line is: https://www.bbc.com/mundo
lighthouse "https://www.bbc.com/mundo" --quiet --chrome-flags="--headless" --out
put=json --output-path="C:\Users\Owner\Desktop\Folder\Lighthouse_Project\json_lo
gs\08-10-201916-12-44-14.json"
Line is: https://regex101.com/
lighthouse "https://regex101.com/" --quiet --chrome-flags="--headless" --output=
json --output-path="C:\Users\Owner\Desktop\Folder\Lighthouse_Project\json_logs\0
8-10-201916-12-46-12.json"
Line is: https://www.bbc.co.uk/news
lighthouse "https://www.bbc.co.uk/news" --quiet --chrome-flags="--headless" --ou
tput=json --output-path="C:\Users\Owner\Desktop\Folder\Lighthouse_Project\json_l
ogs\08-10-201916-12-48-21.json"
Press any key to continue . . .

Your issue, as originally stated, was the inclusion of % characters in your initial set syntax, as you can see from the provided output.