find some word in text list file and a bit change to them

[RolanRoll]

hi
I need to find some word in my text list file for example V_20220412 in
S1A_IW_SLC__1SDV_20220412T022912_20220412T022940_042734_05197D_3860

then i want to omit " _" so then , it is like this: V20220412
and then i want to get one day before this date : V20220411
after doing these steps for all rows in text list file ,I want to save them in another text file like this:
V20220411
V20220318
V20220222
V20220128
V20220105

[ibreeden]

Use "re" (regular expression) to find the desired string. Use "datetime" to do date arithmetic.
Show us your program, and we will help you.

[BashBedlam]

Are you searching for exactly V_20220412or do you need every occurrence of an eight character sequence that begins withV_or something else?

[RolanRoll]

hi
first of all i appreciate your help (you and ibreeden) and as you can see in my file names in text list file (below) the date repeated 2 times in every file names (in fore example text list file) but with different times (T= time) i need just date with letter V before because i need the text file that you named it before : "pattern_list.txt" ( your previous code for solving my previous post ) in https://python-forum.io/thread-37560.html
so i know you understand what i exactly need (good job) .i have tried to say my problem in two parts(2 posts) because i say these 2 posts in one question , many times ago and i cannot get answer of any body.
S1A_IW_SLC__1SDV_20220412T022912_20220412T022940_042734_05197D_3860
S1A_IW_SLC__1SDV_20220223T022912_20220223T022940_042034_0501CA_70EF
so for every rows in my text list file (or every file name) , i need to find just one repeated date joined with V and then subtract one day fore all of them (so it should be formatted as date ):
V20220411
V20220222