Google Colab でffmpegのシェルスクリプトが動きません。

Google Colabで、シェルスクリプトを読み込んで実行させたいのですが、ffmpegに限って動きません。よろしくお願いいたします。

bash
1ffmpeg -i a.mp4 b.mp4

Python
1!sh test.sh

Log
1: not found
2ffmpeg version 3.4.6-0ubuntu0.18.04.1 Copyright (c) 2000-2019 the FFmpeg developers
3  built with gcc 7 (Ubuntu 7.3.0-16ubuntu3)
4  configuration: --prefix=/usr --extra-version=0ubuntu0.18.04.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
5  libavutil      55. 78.100 / 55. 78.100
6  libavcodec     57.107.100 / 57.107.100
7  libavformat    57. 83.100 / 57. 83.100
8  libavdevice    57. 10.100 / 57. 10.100
9  libavfilter     6.107.100 /  6.107.100
10  libavresample   3.  7.  0 /  3.  7.  0
11  libswscale      4.  8.100 /  4.  8.100
12  libswresample   2.  9.100 /  2.  9.100
13  libpostproc    54.  7.100 / 54.  7.100
14Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'data.mp4':
15  Metadata:
16    major_brand     : isom
17    minor_version   : 512
18    compatible_brands: isomiso2avc1mp41
19    encoder         : Lavf57.83.100
20  Duration: 00:00:11.76, start: 0.000000, bitrate: 3254 kb/s
21    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 3251 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
22    Metadata:
23      handler_name    : VideoHandler
24'
25: Invalid argument
26