For windows users:
create video2gif.bat file in windows directory with these content:

@echo off
set arg1=%1
set arg2=%arg1:~0,-4%
ffmpeg -y -i %arg1% -vf fps=10,scale=-1:-1:flags=lanczos,palettegen %TEMP%\palette.png
ffmpeg -i %arg1% -i %TEMP%\palette.png -filter_complex "fps=10,scale=-1:-1:flags=lanczos[x];[x][1:v]paletteuse" %arg2%.gif
del /f %TEMP%\palette.png

And then anywhere you can use it be like this example:

video2gif myvideo.mp4

Then you have myvideo.gif in current directory.
If myvideo.gif there is existed, question from you for overwrite it.

EDIT:

I suggest use this batch script: https://github.com/NabiKAZ/video2gif

For Windows users: create a file \Windows\video2gif.bat with this content:

@echo off
set arg1=%1
set arg2=%arg1:~0,-4%
ffmpeg -y -i %arg1% -vf fps=10,scale=-1:-1:flags=lanczos,palettegen %TEMP%\palette.png
ffmpeg -i %arg1% -i %TEMP%\palette.png -filter_complex "fps=10,scale=-1:-1:flags=lanczos[x];[x][1:v]paletteuse" %arg2%.gif
del /f %TEMP%\palette.png

And then you can use it anywhere like this:

video2gif myvideo.mp4

Then you have myvideo.gif next to your original input file. If myvideo.gif already exists, you will be asked to overwrite it.

I suggest using this versatile batch script.

For windows users:
create video2gif.bat file in windows directory with these content:

@echo off
set arg1=%1
set arg2=%arg1:~0,-4%
ffmpeg -y -i %arg1% -vf fps=10,scale=-1:-1:flags=lanczos,palettegen %TEMP%\palette.png
ffmpeg -i %arg1% -i %TEMP%\palette.png -filter_complex "fps=10,scale=-1:-1:flags=lanczos[x];[x][1:v]paletteuse" %arg2%.gif
del /f %TEMP%\palette.png

And then anywhere you can use it be like this example:

video2gif myvideo.mp4

Then you have myvideo.gif in current directory.
If myvideo.gif there is existed, question from you for overwrite it.

For windows users:
create video2gif.bat file in windows directory with these content:

@echo off
set arg1=%1
set arg2=%arg1:~0,-4%
ffmpeg -y -i %arg1% -vf fps=10,scale=-1:-1:flags=lanczos,palettegen %TEMP%\palette.png
ffmpeg -i %arg1% -i %TEMP%\palette.png -filter_complex "fps=10,scale=-1:-1:flags=lanczos[x];[x][1:v]paletteuse" %arg2%.gif
del /f %TEMP%\palette.png

And then anywhere you can use it be like this example:

video2gif myvideo.mp4

Then you have myvideo.gif in current directory.
If myvideo.gif there is existed, question from you for overwrite it.

EDIT:

I suggest use this batch script: https://github.com/NabiKAZ/video2gif