Shell – Remove all files created before a certain date

Another complicated option:

1. get test.txt's modification time (mtime)
2. calculate "before delta" = now + hour - mtime (assuming mtime is in the past)
3. calculate "after delta" = now - hour - mtime if now - mtime > hour else 0
4. run find -type f -mmin -"before delta" -mmin +"after delta"

It finds all files that are modified less than "before delta" minutes ago and greater than "after delta" minutes ago i.e., +/- hour around test.txt's modification time.

It might be simpler to understand if you draw now, mtime, "before", "after" times on a line.

date command allows to get now and mtime.

As a one-liner:

$ find -type f -newermt "$(date -r $file) -1 hour" -a \
            \! -newermt "$(date -r $file) +1 hour"

portably:

cd &&
  find . -path ./junk -prune -o -type f \( \
    -name '*.h' -o -name '*.cpp' \) -exec sh -c '
      exec mv -i "$@" junk' sh {} +

Above excluding the junk folder itself from the search.

We're only removing regular files (-type f). There may be other types of files you want to move like symlinks, but beware that moving symlinks often break them.

The -i is a safeguard to avoid two files with the same name overriding each other.