Compare logged data on SD card to current reading - £25 for working answer

right i have narrowed down the issue

 // This section is for storing values to SD card
  myFile = SD.open("Nautilus.txt", FILE_WRITE);
  if (myFile) { 

    char line[26]; // 25 characters plus null terminator 26
    //char time1[11];
    //dtostrf(now.unixtime(),10,2,time1);
    char temp[7];
    dtostrf(T1, 6, 2, temp); // Convert float to string.
    char press1[8];
    dtostrf((L1*10), 7, 2, press1);
    sprintf(line, "%10d %10s %6s %7s", now.unixtime(), temp, press1);
    myFile.println(line); // writes a 25-character string plus a \n so 26 characters to the file - that's one line.
    Serial.println(line);

    
    Serial.println(now.unixtime());

    myFile.close(); // close the file   
  }

I edited one of your line "sprintf(line, "%10d %10s %6s %7s", now.unixtime(), temp, press1);" to see if it would make any difference (I added %10s). that is when i started getting -32516 M~1 below. Before i added %10s that first part of the code did not print out.

this is what i can see on the serial monitor

SD card is ready to use.
    -32516    M~1     23.96   36.70
---
    -32506    M~1     23.92   34.59
---
    -32496    M~1     23.88   36.00
---
    -32486    M~1     23.83   34.59
---
    -32476    M~1     23.76   33.89
---
    -32466    M~1     23.71   33.89
---
    -32456    M~1     23.67   31.79
---
    -32446    M~1     23.62   34.59
---
    -32436    M~1     23.58   35.30
---
    -32426    M~1     23.55   29.69
---
    -32416    M~1     23.51   34.59
---
    -32406    M~1     23.48   34.59
---
    -32396    M~1     23.45   33.19
---
    -32386    M~1     23.42   31.79
---
    -32376    M~1     23.41   34.59
---
    -32366    M~1     23.39   33.19
---

and the following is on the SD card

    -32516    M~1     23.96   36.70
    -32506    M~1     23.92   34.59
    -32496    M~1     23.88   36.00
    -32486    M~1     23.83   34.59
    -32476    M~1     23.76   33.89
    -32466    M~1     23.71   33.89
    -32456    M~1     23.67   31.79
    -32446    M~1     23.62   34.59
    -32436    M~1     23.58   35.30
    -32426    M~1     23.55   29.69
    -32416    M~1     23.51   34.59
    -32406    M~1     23.48   34.59
    -32396    M~1     23.45   33.19
    -32386    M~1     23.42   31.79
    -32376    M~1     23.41   34.59
    -32366    M~1     23.39   33.19
    -32356    M~1     23.37   34.59
    -32346    M~1     23.35   33.89
    -32336    M~1     23.32   31.09
    -32326    M~1     23.28   33.19
    -32316    M~1     23.24   34.59
    -32306    M~1     23.21   33.19

From what i can tell there seem to be an issue with the time being added.