cURL
cURL is a command line tool and library for transferring data with URLs. The command supports a number of different protocols, including HTTP, HTTPS, FTP, SCP, and SFTP. It is also designed to work without user interaction, like in scripts.
Installation
Usage
Downloading
A common use case for cURL is to download the resource to a specified file:
$ curl --output file name URL
If the URL contains the file name, you can save the resource directly to a file of that name:
$ curl --remote-name URL
Similarly, you can use -J/--remote-header-name
to accept a hint from an HTTP server (from the Content-Disposition
header) for what the file should be named. If combined with -O/--remote-name
, curl will use the file name specified by the URL if the HTTP server does not return a file name hint in its response.
Alternatively you can print the resource to stdout by omitting the output options:
$ curl URL
HTTP POST
You can use cURL to make HTTP POST requests:
$ curl --data 'request body' URL
If the request body cannot fit on the command line, cURL can read it from a file:
$ curl --data @file name URL
Sometimes, you may need to specify a custom value for the Content-Type
header (cURL's default is application/x-www-form-urlencoded
). You can do this with -H
. For example, if you wanted to make a POST request with a JSON body:
$ curl --data 'json body' -H 'Content-Type: application/json' URL
note that curl also has a option to write post data in json and change those headers automatically: --json
:
$ curl --json '{"key":"value"}' URL
Tips and tricks
Following redirects
To follow redirects (e.g. an HTTP to HTTPS redirect):
$ curl --location URL
Show download errors
By default curl would ignore errors (e.g. when downloading to a file, if there is a error curl would not notify you, and the file would be created empty) so use --fail
to make it show a message on error:
$ curl --fail URL
Compression
If you want to transfer the data compressed[dead link 2024-07-30 ⓘ], (e.g. in situations where bandwidth is more limited than CPU, curl would download the data compressed then uncompressed it after the downlod):
$ curl --compressed URL
ProgressBar
curl has option to a normal ProgressBar when it download files (e.g. [##### ] 80%
)
$ curl --progress-bar URL
Globbing
You can also use globing[dead link 2024-07-30 ⓘ] in curl:
$ curl "example.com/images/[1-9].png" $ curl "example.com/{first_page,second_page,third_page}"
config file
curl also search for a config file called .curlrc
in home directory and in $XDG_CONFIG_HOME
. You can just put the command line argument you want to use with curl by default, for example :
$HOME/.curlrc
# this is a comment, the next line would be the option for progressbar: -# # to make curl always compress: --compressed # or just compressed
See also
- Wikipedia:cURL
- Everything curl - Extensive guide to using cURL
- curl(1)