Curl#

#

Introduction#

Curl is a tool for transferring data between servers, supporting protocols, including:

HTTP
HTTPS
FTP
IMAP
LDAP
POP3
SCP
SFTP
SMB
SMTP
etc…

Curl GitHub source repository (github.com)
Curl Official Website (curl.se)

Options#

-o <file>    # --output: write to file
-u user:pass # --user: authentication

-v   # --verbose: Make curl verbose during operation
-vv  # more verbose
-s   # --silent: don't show progress meter or errors
-S   # --show-error: When used with --silent (-sS), show errors but no progress meter

-i  # --include: include HTTP headers in the output
-I  # --head: header only

Request#

-X POST # --request
-L # If the page redirects, follow the link
-F # --form: HTTP POST data for multipart/form-data

data#

# --data: HTTP post data
# URL encoding (eg, status="Hello")
-d 'data'

# --data pass file
-d @file

# --get: send -d data via get
-G

Header information Headers#

-A <str>      # --user-agent

-b name=val   # --cookie

-b, --cookie FILE           # Load cookies from the specified file for the URL
-c, --cookie-jar FILE       # Save cookies to the specified file from the URL

-H "X-Foo: y" # --header

--compressed  # use deflate/gzip

SSL#

    --cacert <file>
    --capath <dir>

-E, --cert <cert> # --cert: client certificate file
    --cert-type # der/pem/eng
-k, --insecure # For self-signed certificates

Install#

apk add --update curl # install in alpine linux

Example#

CURL GET/HEAD#

command	description
`curl -I https://cheatsheets.zip`	`curl` sends a request
`curl -v -I https://cheatsheets.zip`	`curl` request with details
`curl -X GET https://cheatsheets.zip`	use explicit http method for `curl`
`curl --noproxy 127.0.0.1 http://www.stackoverflow.com`	`curl` without http proxy
`curl --connect-timeout 10 -I -k https://cheatsheets.zip`	`curl` has no timeout by default
`curl --verbose --header "Host: www.mytest.com:8182" cheatsheets.zip`	`curl` get extra header
`curl -k -v https://www.google.com`	`curl` get response with headers

Multiple file upload#

$ curl -v --include \
--form key1=value1 \
    --form upload=@localfilename URL

Prettify json output for curl response#

$ curl -XGET http://${elasticsearch_ip}:9200/_cluster/nodes | python -m json.tool

CURL POST#

command	description
`curl -d "name=username&password=123456" <URL>`	`curl` send request
`curl <URL> -H "content-type: application/json" -d "{ \"woof\": \"bark\"}"`	`curl` sends json

CURL script install rvm#

curl -sSL https://get.rvm.io | bash

CURL Advanced#

command	description
`curl -L -s http://ipecho.net/plain, curl -L -s http://whatismijnip.nl`	get my public `IP`
`curl -u $username:$password http://repo.dennyzhang.com/README.txt`	`curl` with credentials
`curl -v -F key1=value1 -F upload=@localfilename <URL>`	`curl` upload
`curl -k -v --http2 https://www.google.com/`	use http2 curl
`curl -T cryptopp552.zip -u test:test ftp://10.32.99.187/`	curl `ftp` upload
`curl -u test:test ftp://10.32.99.187/cryptopp552.zip -o cryptopp552.zip`	curl `ftp` download
`curl -v -u admin:admin123 --upload-file package1.zip http://mysever:8081/dir/package1.zip`	upload with credentials `curl`

Check website response time#

curl -s -w \
'\nLookup time:\t%{time_namelookup}\nConnect time:\t%{time_connect}\nAppCon time:\t%{time_appconnect}\nRedirect time:\t%{time_redirect}\nPreXfer time:\t%{time_pretransfer }\nStartXfer time:\t%{time_starttransfer}\n\nTotal time:\t%{time_total}\n' \
     -o /dev/null https://www.google.com

Use Curl to check if a remote resource is available#

curl -o /dev/null --silent -Iw "%{http_code}" https://example.com/my.remote.tarball.gz

Downloading file#

curl https://example.com | \
grep --only-matching 'src="[^"]*.[png]"' | \
cut -d \" -f2 | \
while read i; do curl https://example.com/"${i}" \
-o "${i##*/}"; done

Download all PNG files from the site (using GNU grep)

Download the file, save the file without changing its name#

curl --remote-name "https://example.com/linux-distro.iso"

Rename file

curl --remote-name "http://example.com/index.html" --output foo.html

continue partial download#

curl --remote-name --continue-at -"https://example.com/linux-distro.iso"

Download files from multiple domains#

curl "https://www.{example,w3,iana}.org/index.html" --output "file_#1.html"

Download a series of files#

curl "https://{foo,bar}.com/file_[1-4].webp" --output "#1_#2.webp"

Download a series of files (output foo_file1.webp, foo_file2.webp...bar_file1_webp, etc.)

Redirect output to file#

$ curl http://url/file > file

Basic Authentication#

$ curl --user username:password http://example.com/
$ curl -u username:password http://example.com/

Write to file instead of stdout#

$ curl -o file http://url/file
$ curl --output file http://url/file

Download header information#

$ curl -I url
# display header information

Write output to a file named remote_file#

$ curl -o file http://url/file
$ curl --output file http://url/file

Execute remote script#

$ curl -s http://url/myscript.sh

Configuration file#

curl -K file
# read configuration from file
curl --config file
$HOME/.curlrc # default configuration file on UNIX-like systems

Curl

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