FFMPEG concat video throws No Such Filter error

I am trying to concat three videos using FFMPEG,

This is my command that I am executing using Java Runtime

    String command = "ffmpeg -i url_to_video -i url_to_video -i url_to_video -filter_complex [0:v] [0:a] [1:v] [1:a] [2:v] [2:a] concat=n=3:v=1:a=1 [v] [a] -map [v] -map [a] /home/rohan/output.mp4";

    Process process = Runtime.getRuntime().exec(command.split(" "));

This is throwing me No Such Filter error, whereas if I try to run this via Terminal it works perfectly fine. I tried tweaking the cmd by removing or adding quotes, but any variant of this command that runs on terminal throws error in Java Runtime. While it runs perfectly on the Terminal.

I have tried with Absolute paths and Amazon S3 URLs, while both of them work just fine in terminal, The S3 variant of command throws No Such Filter error and the Absolute path command throws a No Such File Or Directory error during Runtime.

Here is the stack trace of the error

Here is the standard error of the command (if any):

ffmpeg version n4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 7 (Ubuntu 7.5.0-3ubuntu1~18.04)
  configuration: --prefix= --prefix=/usr --disable-debug --disable-doc --disable-static --enable-cuda --enable-cuda-sdk --enable-cuvid --enable-libdrm --enable-ffplay --enable-gnutls --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfontconfig --enable-libfreetype --enable-libmp3lame --enable-libnpp --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopus --enable-libpulse --enable-sdl2 --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libv4l2 --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxvid --enable-nonfree --enable-nvenc --enable-omx --enable-openal --enable-opencl --enable-runtime-cpudetect --enable-shared --enable-vaapi --enable-vdpau --enable-version3 --enable-xlib
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'https://openxcell-development-public.s3.ap-south-1.amazonaws.com/bhit/outputForBHit.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:10.57, start: 0.000000, bitrate: 2048 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 1696 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, 5.1, fltp, 347 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'https://openxcell-development-public.s3.ap-south-1.amazonaws.com/bhit/outputForBHit.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:10.57, start: 0.000000, bitrate: 2048 kb/s
    Stream #1:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 1696 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #1:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, 5.1, fltp, 347 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #2, mov,mp4,m4a,3gp,3g2,mj2, from 'https://openxcell-development-public.s3.ap-south-1.amazonaws.com/bhit/outputForBHit.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:10.57, start: 0.000000, bitrate: 2048 kb/s
    Stream #2:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 1696 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #2:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, 5.1, fltp, 347 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
[AVFilterGraph @ 0x564151595680] No such filter: ''
Error initializing complex filters.
Invalid argument

Answer

If you are going to supply the filtergraph string without quotes, it must not have any (unquoted / unescaped spaces)

So, instead of

-filter_complex [0:v] [0:a] [1:v] [1:a] [2:v] [2:a] concat=n=3:v=1:a=1 [v] [a]

it may be

-filter_complex [0:v][0:a][1:v][1:a][2:v][2:a]concat=n=3:v=1:a=1[v][a]