Use `less +F` on multiple files merged into a single stream, just like `tail -f`

lessf.sh

# lessf: `less +F` for multiple files, ala `tail -f`
#
# Usage:
#    lessf file1.log file2.log ...
#
#  - should work on dash, bash, and zsh;
#  - works on macOS and the Linuxes I've tested it on;
#  - requires the minimal tools that seem to be available nearly everywhere (`awk`, `mktemp`), and of course `less`
#  - you may want `unbuffer` or `stdbuf` to avoid the 4kb of buffering (i.e. no output until enough loglines have been added.)
#
# See also, if you can install Actual Software, and want a ncurses-based tool or more features:
#    <https://www.vanheusden.com/multitail/>
lessf() (
   if ! command -v unbuffer >&/dev/null; then
      if unb_bin="$(command -v stdbuf)"; then
         unbuffer() { "$unb_bin" -o0 "$@" ;}

      else
         printf "WARN: You probably want \`unbuffer\` from the 'expect' package or \`stdbuf\` from 'coreutils'.\n" >&2
         printf "WARN: Without them, output is buffered, and loglines may not appear immediately!\n" >&2
         sleep 5
      fi
   fi

   pad="7"
   for arg in "$@"; do
      fname="${arg##*/}"
      fname="${fname%.log}"
      if [ ${#fname} -gt "${pad}" ]; then
         pad="${#fname}"
      fi
   done

   tmpfile="$(mktemp "$TMPDIR/lessf.XXXXXX")"
   # shellcheck disable=SC2064
   trap "rm -f '$tmpfile'; trap - EXIT" EXIT INT HUP QUIT TERM

   printf "Following" >"$tmpfile"
   printf " '%s'," "$@" >>"$tmpfile"
   unbuffer tail -n10 -f "$@" \
      | awk "$(cat <<AWK
         # Drop blank lines
         /^$/ {next};

         # If the line starts with '==>', split the path and store the components in 'cmp'
         /^==> / {
            n = split(substr(\$0, 5, length - 8), cmp, "/")
            sub(/\.log\$/, "", cmp[n])
            next
         }

         # Print the last component of the path prepended to the logline
         {
            printf "%${pad}s: %s\n", cmp[n], \$0
         }
AWK
   )" >>"$tmpfile" &

   less -SRX +F "$tmpfile"
)