find.1 "$lastepochfile" -mtime -1
search for files in a directory hierarchy
find [-H] [-L] [-P] [-D debugopts] [-Olevel] [path...] [expression]
-mtime n
       File's  data  was  last  modified  n*24  hours ago.  See the comments for -atime to understand how
       rounding affects the interpretation of file modification times.
source manpages: find