$ ffmpeg  -framerate 8 -pattern_type glob -i "*.jpg" ../t-no-split.gif
ffmpeg version n4.2.1 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 9.1.0 (GCC)
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-nvdec --enable-nvenc --enable-omx --enable-shared --enable-version3
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Input #0, image2, from '*.jpg':
  Duration: 00:00:05.25, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: mjpeg (Baseline), yuvj420p(pc, bt470bg/unknown/unknown), 1080x1080 [SAR 1:1 DAR 1:1], 8 fps, 8 tbr, 8 tbn, 8 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> gif (native))
Press [q] to stop, [?] for help
[swscaler @ 0x5605d34192c0] deprecated pixel format used, make sure you did set range correctly
[swscaler @ 0x5605d34192c0] No accelerated colorspace conversion found from yuv420p to bgr8.
Output #0, gif, to '../t-no-split.gif':
  Metadata:
    encoder         : Lavf58.29.100
    Stream #0:0: Video: gif, bgr8, 1080x1080 [SAR 1:1 DAR 1:1], q=2-31, 200 kb/s, 8 fps, 100 tbn, 8 tbc
    Metadata:
      encoder         : Lavc58.54.100 gif
[swscaler @ 0x5605d329d240] deprecated pixel format used, make sure you did set range correctly
[swscaler @ 0x5605d329d240] No accelerated colorspace conversion found from yuv420p to bgr8.
frame=   42 fps=0.0 q=-0.0 Lsize=    8372kB time=00:00:05.14 bitrate=13342.8kbits/s speed=8.93x
video:8372kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000233%