segment, stream_segment, ssegment
       Basic stream segmenter.

       This  muxer  outputs  streams  to  a number of separate files of nearly
       fixed duration. Output filename pattern can be set in a fashion similar
       to image2, or by using a "strftime" template if the strftime option  is
       enabled.

       "stream_segment"  is  a variant of the muxer used to write to streaming
       output formats, i.e. which  do  not  require  global  headers,  and  is
       recommended  for  outputting  e.g.  to  MPEG transport stream segments.
       "ssegment" is a shorter alias for "stream_segment".

       Every segment starts with a keyframe of the selected reference  stream,
       which is set through the reference_stream option.

       Note  that if you want accurate splitting for a video file, you need to
       make the input key frames  correspond  to  the  exact  splitting  times
       expected  by  the  segmenter,  or  the segment muxer will start the new
       segment with the key frame found next after the specified start time.

       The segment muxer works best with a single constant frame rate video.

       Optionally it can generate a list of the created segments,  by  setting
       the   option   segment_list.   The   list  type  is  specified  by  the
       segment_list_type option. The entry filenames in the segment  list  are
       set by default to the basename of the corresponding segment files.

       See  also  the hls muxer, which provides a more specific implementation
       for HLS segmentation.

       Options

       The segment muxer supports the following options:

[...]

From the image2 section, here is how the filename pattern works:

           sequence
               Select  a  sequence pattern type, used to specify a sequence of
               files indexed by sequential numbers.

               A sequence pattern may contain the string "%d" or "%0Nd", which
               specifies  the  position  of  the  characters  representing   a
               sequential  number  in each filename matched by the pattern. If
               the form "%d0Nd" is used, the string representing the number in
               each filename is 0-padded and N is the total number of 0-padded
               digits representing the number. The literal character  '%'  can
               be specified in the pattern with the string "%%".

               If  the  sequence  pattern  contains  "%d" or "%0Nd", the first
               filename of the file list specified by the pattern must contain
               a  number  inclusively  contained  between   start_number   and
               start_number+start_number_range-1,   and   all   the  following
               numbers must be sequential.

               For example the pattern "img-%03d.bmp" will match a sequence of
               filenames  of   the   form   img-001.bmp,   img-002.bmp,   ...,
               img-010.bmp,  etc.;  the  pattern "i%%m%%g-%d.jpg" will match a
               sequence of filenames of  the  form  i%m%g-1.jpg,  i%m%g-2.jpg,
               ..., i%m%g-10.jpg, etc.

And btw, the ffmpeg-formats manual does also include examples:

       Examples

       •   Remux the content of file in.mkv to a list of segments out-000.nut,
           out-001.nut, etc., and write the  list  of  generated  segments  to
           out.list:

                   ffmpeg -i in.mkv -codec hevc -flags +cgop -g 60 -map 0 -f segment -segment_list out.list out%03d.nut

       •   Segment  input  and  set  output  format  options  for  the  output
           segments:

                   ffmpeg -i in.mkv -f segment -segment_time 10 -segment_format_options movflags=+faststart out%03d.mp4

       •   Segment the input file according to the split points  specified  by
           the segment_times option:

                   ffmpeg -i in.mkv -codec copy -map 0 -f segment -segment_list out.csv -segment_times 1,2,3,5,8,13,21 out%03d.nut

       •   Use  the  ffmpeg force_key_frames option to force key frames in the
           input at the specified location, together with the  segment  option
           segment_time_delta  to account for possible roundings operated when
           setting key frame times.

                   ffmpeg -i in.mkv -force_key_frames 1,2,3,5,8,13,21 -codec:v mpeg4 -codec:a pcm_s16le -map 0 \
                   -f segment -segment_list out.csv -segment_times 1,2,3,5,8,13,21 -segment_time_delta 0.05 out%03d.nut

           In order to force key frames on  the  input  file,  transcoding  is
           required.

       •   Segment the input file by splitting the input file according to the
           frame numbers sequence specified with the segment_frames option:

                   ffmpeg -i in.mkv -codec copy -map 0 -f segment -segment_list out.csv -segment_frames 100,200,300,500,800 out%03d.nut

       •   Convert  the  in.mkv  to  TS segments using the "libx264" and "aac"
           encoders:

                   ffmpeg -i in.mkv -map 0 -codec:v libx264 -codec:a aac -f ssegment -segment_list out.list out%03d.ts

       •   Segment the input file, and create an M3U8 live  playlist  (can  be
           used as live HLS source):

                   ffmpeg -re -i in.mkv -codec copy -map 0 -f segment -segment_list playlist.m3u8 \
                   -segment_list_flags +live -segment_time 10 out%03d.mkv

It is actually possible to figure out how to do this and many other ffmpeg tasks even without internet access :)