curl

Downloading Files

Simple download

curl -O https://example.com/file.zip

Download with output filename

curl -o myfile.zip https://example.com/file.zip

Use -L to follow redirects:

curl -L https://example.com

Authentication

Example of using curl with basic auth credentials

curl -u username:password staging.example.com

Send Mail

Please note: Gmail no longer supports "less secure apps." Use App Passwords instead.

curl --ssl-reqd --url 'smtps://smtp.gmail.com:465' \
--user '[email protected]:app_password' \
--mail-from '[email protected]' \
--mail-rcpt '[email protected]' \
--upload-file mail.txt

mail.txt file contents:

From: "User Name" <[email protected]>
To: "John Smith" <[email protected]>
Subject: This is a test

Hi John,
I’m sending this mail with curl thru my gmail account.
Bye!

Use --netrc-file instead of credentials in curl command for better security.

Example:

curl --netrc-file ~/.netrc staging.example.com

machine staging.example.com
login username
password password

WebDAV

Create directories on WebDAV:

curl -X MKCOL 'http://your.server/uploads/nested_folder1' --user 'name:pwd'

Upload a file via WebDAV:

curl -T file.txt 'http://your.server/uploads/file.txt' --user 'username:password'

Upload all files in folder (directories must exist):

cd local_folder_to_upload && find . -type f -exec curl -T {} 'http://your.server/uploads/{}' --user 'username:password' \;

Random Examples

check netowrk range

Example to check /24 range in "abuseipdb.com" for the last 3 days

DAYS=3
curl -s -G "https://api.abuseipdb.com/api/v2/check-block" \
  --data-urlencode "network=123.123.123.1/24" \
  -d "maxAgeInDays=$DAYS" \
  -H "Key: apikeyfromabuseipdb.com" \
  -H "Accept: application/json" \
  | jq '.data.reportedAddress'

If you dont have jq installed:

• ubuntu: sudo apt install jq
• windows: scoop install jq

Inspect headers

If you want to inspect the headers of a response from some endpoint include the -I flag and curl will return just the headers.

curl -I localhost:3000/posts

or a verbose setting:

curl -v localhost:3000/posts

Request JSON

Query a website e.g. request a json response from cloudflare-dns.com on TXT records of the domain 0xfab1.net

curl -s -H 'accept: application/dns-json' 'https://cloudflare-dns.com/dns-query?name=0xfab1.net&type=TXT'

Send JSON

This command sends a POST request with JSON data.

curl -X POST https://api.example.com/posts \
-H 'Content-Type: application/json' \
-d '{"title":"Hello","body":"Curl"}'

Timing

This command measures the performance of a request.

It shows:

• DNS lookup time (time_namelookup)
• TCP connection time (time_connect)
• total request duration (time_total)

The response body is ignored (-o /dev/null).

curl -w "@-" -o /dev/null -s "https://example.com" <<'EOF'
time_namelookup: %{time_namelookup}\n
time_connect: %{time_connect}\n
time_total: %{time_total}\n
EOF

Using a proxy

Route the request through a proxy server (http://proxyserver:port). This is useful for debugging, bypassing restrictions, or accessing internal networks.

curl -x http://proxyserver:port https://example.com

More

• Use curl with ssl

Absolutely! Here’s the technical blog section in Markdown:

Is curl in PowerShell an Alias or the Real Deal?

On Windows, running curl in PowerShell might not always do what you expect. That’s because older versions of PowerShell define curl as an alias for Invoke-WebRequest, while modern Windows also ships with the real cURL executable. To avoid confusion, here’s a simple PowerShell snippet to check exactly what curl points to in your session:

$curlCmd = Get-Command curl -ErrorAction SilentlyContinue

if ($null -eq $curlCmd) {
    Write-Output "'curl' is not available in your PATH."
}
elseif ($curlCmd.CommandType -eq 'Alias') {
    Write-Output "'curl' is a PowerShell alias for '$($curlCmd.Definition)'."
}
elseif ($curlCmd.CommandType -eq 'Application') {
    Write-Output "'curl' is the real executable located at: $($curlCmd.Source)"
}
else {
    Write-Output "Unexpected command type: $($curlCmd.CommandType)"
}

Just run this script in your PowerShell window, and you’ll immediately know whether curl is an alias or the real command-line tool. If it’s an alias and you need the actual cURL, you can always remove the alias for your session with:

Remove-Item alias:curl