= Curl =

'''`curl(1)`''' is a command-line tool for fetching internet (chiefly web or FTP) content.

The project (which encompasses both `curl(1)` and libcurl) is stylized as '''cURL''', and stands for "Client URL".

<<TableOfContents>>

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== Installation ==

All [[Linux]] and [[BSD]] distributions offer a `curl` package.

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== Usage ==

{{{
curl -output path/to/file URL
}}}

If the `output` option is not specified, the response will be written to `STDOUT`.

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== Tips ==

=== Suppressing Progress Bar ===

{{{
curl --no-progress-meter https://example.com
}}}



=== Downloading a File ===

{{{
curl --output path/to/file --fail https://example.com
}}}

In the case of a server error (HTTP 4xx), an error page is often returned by the server. The `--fail` option suppresses this page from output and causes `curl(1)` to exit with code 22.



=== Checking Availability ===

{{{
code=$(curl --silent --fail --head --write-out '%{http_code}' https://example.com)
case $code in
  0)
    echo "Success! Server returned HTTP code ${code}"
    ;;
  22)
    echo "Error! Server returned HTTP code ${code}"
    ;;
  6)
    echo "Error! Server not found"
    ;;
  60)
    echo "Error! SSL/TLS certificate cannot be verified"
    ;;
  *)
    echo "Error!"
    ;;
esac
}}}

The `--head` option causes `curl(1)` to only fetch only headers. The `--silent` option suppresses all output, including the progress bar or any returned pages.

The `--write-out` option takes a format string that will be populated with available variables.

Other useful variables:

||'''Name'''        ||'''Contains'''||
||content_type      ||Content type of the document||
||http_version      ||Version of HTTP that was used||
||size_header       ||Number of bytes in downloaded headers||
||size_download     ||Number of bytes in downloaded body and data (i.e. not headers)||
||time_namelookup   ||Number of seconds from start until name was resolved||
||time_connect      ||Number of seconds from start until TCP connection||
||time_appconnect   ||Number of seconds from start until SSL handshake||
||time_pretransfer  ||Number of seconds from start until all pre-transfer steps are complete||
||time_starttransfer||Number of seconds from start until first transferred byte is received||
||time_total        ||Number of seconds||
||speed_download    ||Average number of bytes per second||
||ssl_verify_result ||Result of certificate verification (0 if successful)||

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== See also ==

[[https://man.archlinux.org/man/curl.1|curl(1)]]



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