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Sending various HTTP request kinds using curl

Posted by jpluimers on 2017/07/25

I’ve been using cURL but always had a feeling not to its potential basically because the cURL man page [WayBack] is both massive and lacks concrete useful practical examples.

For instance, I knew about the --header and --verbose options (I always use verbose names even though shorter -H and -v exist) to pass a specific header and get verbose output, but the man page basic examples like this by Tader:

curl --header --verbose "X-MyHeader: 123" http://www.google.com

source: How to send a header using a HTTP request through a curl call? – Stack Overflow [WayBack]

There are some more examples at bropages.org/curl but they’re hardly organised or documented.

So I was really glad I found the below answer [WayBack] by Amith Koujalgi to web services – HTTP POST and GET using cURL in Linux – Stack Overflow.

But first note that recent versions (around 7.22 or higher) of cURL now need to combine the --silent and --show-error (or in short -sS) parameters to suppress progress but show errors: linux – How do I get cURL to not show the progress bar? – Stack Overflow [WayBack]

Back to the examples

web services – HTTP POST and GET using cURL in Linux – Stack Overflow has these covered:

  • Request types (--request aka -X):
    • GET of
      • XML (with --header).
      • JSON (with --include and --header).
    • POST of
      • parameters and @file content using --data aka -d.
      • form with file upload using --form (and again @file content).
      • logging in using --location aka -L 30x redirect following and header saving/loading using --dump-header aka -D and --cookie aka -b.
  • Saving output to a file using the >> redirect or --output aka -o (you might want to consider using --remote-name aka -O here).
  • Tips for pretty printing
    • JSON using
      • npm installing the nodejs package json.
      • pip for python installing the pjson package.
      • gem for ruby installing the colorful_json gem.
      • linux using the yajl-tools package.
    • XML using
      • linux using the libxml2-utils package
      • linux using the tidy package.

–jeroen

PS: Just discovered someone wrote a Unicode compatible Delphi wrapper for some of the libcurl [WayBack] functionality.

One Response to “Sending various HTTP request kinds using curl”

  1. You have also a TCurlHTTP class defined in https://github.com/synopse/mORMot/blob/master/SynCrtSock.pas which works under Windows, but also under Linux, OSX and BSD via FPC.

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