-J should truly mean "allow the server to select the file name"

From: Robin A. Meade via curl-users <curl-users_at_lists.haxx.se>
Date: Tue, 12 Oct 2021 15:48:49 -1000

I read at
https://daniel.haxx.se/blog/2020/09/10/store-the-curl-output-over-there/
that -J means "allow the server to select the file name."

Currently, when determining what filename the server selected, curl's -J
option considers only the 'content-disposition' header.

When -L, --location option is used, and the 'content-disposition' header
is absent, I propose that the -J option also consider the file part of
any redirect location.

With this change, the documentation of the -J option would need a new
paragraph:


-J,  --remote-header-name

     (HTTP) This option tells the -O, --remote-name option to use the
     server-specified Content-Disposition filename instead of
     extracting a filename from the URL.

+ When used in combination with -L, --location option and no
+ Content-Disposition is sent, the file part of any location
+ the server redirects to will be treated as the server specified
+ file name.

     If the server specifies a file name and a file with that name
     already exists in the current working directory it will not be
     overwritten and an error will occur. If the server doesn't
     specify a file name then this option has no effect.


This came up because I wrote a script to download the discord
application. My script included the following curl invocation:


   curl -LOJ \
     'https://discordapp.com/api/download?platform=linux&format=tar.gz'


This results in this difficult file name:


   download?platform=linux&format=tar.gz


My colleague changed my script to use wget:


   wget --content-disposition \
     'https://discordapp.com/api/download?platform=linux&format=tar.gz'


which resulted in this nicer file name:


   discord-0.0.16.tar.gz


which is what I get if I download the URL in Firefox or Chrome.

I prefer curl, so I changed it back to this two step curl procedure:


   url='https://discordapp.com/api/download?platform=linux&format=tar.gz'
   url_effective=$(
     curl -sS -L -I "$url" -o /dev/null \
       -w '%{url_effective}'
   )
   curl -O "$url_effective"


I'd prefer the -J option to truly mean "allow the server to select the
file name."

Thank you for considering this change to the -J,  --remote-header-name
option.

Robin

--
Robin A. Meade
robin.a.meade_at_gmail.com
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Received on 2021-10-13