how to using Linux pipe command output another command's help content to a file
Linux tee > >>
gcc help
$ gcc --help
# ???
$ gcc --help | echo > gcc-help.md
# output help to a file
$ gcc --help > gcc-help.md
> && >>
# > overwrite file
$ gcc --help > gcc-help.md
# >> append data
$ gcc --help >> gcc-help.md
total 10 ways
|| visible in terminal || visible in file || existing
Syntax || StdOut | StdErr || StdOut | StdErr || file
==========++==========+==========++==========+==========++===========
> || no | yes || yes | no || overwrite
>> || no | yes || yes | no || append
|| | || | ||
2> || yes | no || no | yes || overwrite
2>> || yes | no || no | yes || append
|| | || | ||
&> || no | no || yes | yes || overwrite
&>> || no | no || yes | yes || append
|| | || | ||
| tee || yes | yes || yes | no || overwrite
| tee -a || yes | yes || yes | no || append
|| | || | ||
n.e. (*) || yes | yes || no | yes || overwrite
n.e. (*) || yes | yes || no | yes || append
|| | || | ||
|& tee || yes | yes || yes | yes || overwrite
|& tee -a || yes | yes || yes | yes || append
tee
# output help to a file
$ gcc --help | tee gcc-help.txt
# > overwrite file
$ gcc --help > gcc-help.txt
# >> append data
$ gcc --help >> gcc-help.txt
refs
https://askubuntu.com/questions/420981/how-do-i-save-terminal-output-to-a-file
https://en.wikipedia.org/wiki/Standard_streams#Standard_error_.28stderr.29
https://askubuntu.com/questions/38126/how-to-redirect-output-to-screen-as-well-as-a-file
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