Linux curl Command Explained with Examples

September 16, 2021

Introduction

Transferring data to and from a server requires tools that support the necessary network protocols. Linux has multiple tools created for this purpose, the most popular being curl and wget.

This tutorial will show you how to use the curl command and provide you with an exhaustive list of the available options.

Linux curl Command Explained with Examples

Prerequisites

  • Access to the terminal
  • Internet access
  • curl installed

Note: If you do not have curl installed, install it by typing the following in the terminal:

sudo apt install curl

What Is the curl Command?

curl (short for "Client URL") is a command line tool that enables data transfer over various network protocols. It communicates with a web or application server by specifying a relevant URL and the data that need to be sent or received.

curl is powered by libcurl, a portable client-side URL transfer library. You can use it directly on the command line or include it in a script. The most common use cases for curl are:

  • Downloading files from the internet
  • Endpoint testing
  • Debugging
  • Error logging

curl Syntax

The basic curl syntax is as follows:

curl [options/URLs]

For example:

curl https://www.gnu.org/gnu/gnu.html

The system outputs the HTML contents found on the URL provided after the curl command.

HTML contents found on the URL provided after the curl command

If you specify a URL that leads to a file, you can use curl to download the file to your local system:

curl [url] > [local-file]

The progress bar shows how much of the file has been downloaded so far.

The progress bar shows how much of the file has been downloaded

The syntax of URLs that are part of the command depends on the protocol. Multiple URLs that differ in one part are written together using braces:

http://example.{first,second,third}.com

Alphanumeric series are written with brackets:

ftp://ftp.url.com/file[1-100].txt

While nested sequences are not supported, multiple sequences are allowed:

http://url.com/archive[2010-2020]/vol[1-4]/part{a,b,c}.html

curl Protocols

curl supports numerous protocols for data transfer. Find the complete list below.

ProtocolDescription
DICTA dictionary network protocol for querying dictionary servers about the meanings of words.
FILEA URL scheme for obtaining a file from the local file system using curl.
FTP, FTPSFile Transfer Protocol, used for file transfers between clients and servers. FTPS is the version of the same protocol with an added SSL/TLS security layer.
GOPHER, GOPHERSAn old protocol for searching, retrieving, and distributing internet documents, a precursor of HTTP. GOPHERS is the version of the same protocol with an added SSL/TLS security layer.
HTTP, HTTPSHypertext Transfer Protocol, used for web and internet data transfer. HTTPS is the version of the same protocol with an added SSL/TLS security layer.
IMAP, IMAPSInternet Message Access Protocol, used for email access and management. IMAPS is the version of the same protocol with an added SSL/TLS security layer.
LDAP, LDAPSLightweight Directory Access Protocol, used for distributed directory information access and management. LDAPS is the version of the same protocol with an added SSL/TLS security layer.
MQTTMessage Queuing Telemetry Transport - a protocol for data exchange between small devices, usually IoT systems.
POP3, POP3SPost Office Protocol version 3 - a protocol for email retrieval from a server. POP3S is the version of the same protocol with an added SSL/TLS security layer.
RTMPReal-Time Messaging Protocol - a streaming protocol for audio, video, and other data.
RTSPReal Time Streaming Protocol, used for streaming media servers management.
SCPSecure Copy - a protocol for copying files to and from an SSH server.
SFTPSSH File Transfer Protocol - a version of the File Transfer Protocol using the SSH connection.
SMB, SMBSServer Message Block - a protocol for managing shared access to files and computer peripherals. SMBS is the version of the same protocol with an added SSL/TLS security layer.
SMTP, SMPTSSimple Mail Transfer Protocol - an email protocol for easy transmission of email. SMTPS is the version of the same protocol with an added SSL/TLS security layer.
TELNETAn application layer protocol for bidirectional interactive text-oriented communication.
TFTPTrivial File Transfer Protocol, used for uploading or downloading files to or from a remote host.

curl Command Options

curl accepts a wide array of options, which makes it an extremely versatile command. Options start with one or two dashes. If they do not require additional values, the single-dash options can be written together. For example, the command that utilizes the -O, -L, and -v options can be written as:

curl -OLv [url]

The list of all the available options is given below.

OptionDescription
--abstract-unix-socket <path>Connect through abstract Unix socket instead through a network.

Example:
curl --abstract-unix-socket socketpath https://example.com
--alt-svc <file name>Enable alt-svc parser.

Example:
curl --alt-svc svc.txt https://example.com
--anyauthCurl finds and uses the most secure authentication method for the given HTTP URL.

Example:
curl --anyauth --user me:pass https://example.com
-a, --appendAppend to the target file.

Example:
curl --upload-file local --append ftp://example.com/
--aws-sigv4 <provider1[:provider2[:region[:service]]]>Use AWS V4 signature authentication.

Example:
curl --aws-sigv4 "aws:amz:east-2:es" --user "key:secret" https://example.com
--basicUse HTTP basic authentication. 

Example:
curl -u name:password --basic https://example.com
--cacert <file>Use the specified file for certificate verification.

Example:
curl --cacert CA-file.txt https://example.com
--capath <dir>Use the specified directory to look for the certificates.

Example:
curl --capath /local/directory https://example.com
--cert-statusVerify the server certificate status.

Example:
curl --cert-status https://example.com
--cert-type <type>Specify the type of the provided certificate. The recognized types are PEM (default), DER, ENG and P12.

Example:
curl --cert-type ENG --cert file https://example.com
-E, --cert <certificate[:password]>Use the provided certificate file when working with a SSL-based protocol.

Example:
curl --cert certfile --key keyfile https://example.com
--ciphers <list of ciphers>Provide ciphers to be used in the connection.

Example:
curl --ciphers ECDHE-ECDSA-AES256-CCM8 https://example.com
--compressed-sshEnable built-in SSH compression. 

Example:
curl --compressed-ssh sftp://example.com/
--compressedRequest to receive a compressed response. 

Example:
curl --compressed https://example.com 
-K, --config <file>Provide a text file with curl arguments, instead of writing them on the command line. 

Example:
curl --config file.txt https://example.com
--connect-timeout <fractional seconds>Specify maximum time a curl connection may last.

Example:
curl --connect-timeout 30 https://example.com
--connect-to <HOST1:PORT1:HOST2:PORT2>Provide a connection rule to direct requests at a specific server cluster node. 

Example:
curl --connect-to example.com:443:example.net:8443 https://example.com
-C, --continue-at <offset>Resume file transfer at the offset specified.

curl -C 400 https://example.com
-c, --cookie-jar <filename>Specify a file for storing cookies.

curl -c store.txt https://example.com
-b, --cookie <data|filename>Read cookies from a file. 

Example:
curl -b cookiefile https://example.com
--create-dirsCreate the local directories for the --output option. 

Example:
curl --create-dirs --output local/dir/file https://example.com
--create-file-mode <mode>Specify which mode to set upon file creation. 

Example:
curl --create-file-mode 0777 -T localfile sftp://example.com/new
--crlfConvert LF to CRLF. 

curl --crlf -T file ftp://example.com/
--crlfile <file>Provide a Certificate Revocation List for peer certificates. 

curl --crlfile revoke.txt https://example.com
--curves <algorithm list>Provide curves for establishing an SSL session.

Example:
curl --curves X25519 https://example.com
--data-ascii <data>See -d, --data

Example:
curl --data-ascii @file https://example.com
--data-binary <data>Post data as specified, without extra processing. 

curl --data-binary @filename https://example.com
--data-raw <data>Same as -d, --data, but the @ character is not treated differently from the rest. 

curl --data-raw "@at@at@" https://example.com
--data-urlencode <data>Same as -d, --data, but perform URL encoding.

Example:
curl --data-urlencode name=val https://example.com
-d, --data <data>Send data to a HTTP server in a POST request.  

Example:
curl -d "name=curl" https://example.com
--delegation <LEVEL>Specify when the server is allowed to delegate credentials. 

Example:
curl --delegation "always" https://example.com
--digestEnable HTTP Digest authentication. 

Example:
curl -u name:password --digest https://example.com
--disable-eprtDisable EPRT and LPRT commands for active FTP transfers. 

Example:
curl --disable-eprt ftp://example.com/
--disable-epsvDisable EPSV for passive FTP transfers.

Example:
curl --disable-epsv ftp://example.com/
-q, --disableDisable the reading of the curlrc config file.

curl -q https://example.com 
--disallow-username-in-urlExit if provided with a URL that contains a username. 

Example:
curl --disallow-username-in-url https://example.com
--dns-interface <interface>Specify an interface for outgoing DNS requests. 

Example:
curl --dns-interface eth0 https://example.com
--dns-ipv4-addr <address>Specify an IPv4 address from which the DNS requests will come. 

Example:
curl --dns-ipv4-addr 10.1.2.3 https://example.com
--dns-ipv6-addr <address>Specify an IPv6 address from which the DNS requests will come. 

Example:
curl --dns-ipv6-addr 2a04:4e42::561 https://example.com
--dns-servers <addresses>Specify your own list of DNS servers. 

Example:
curl --dns-servers 192.168.0.1,192.168.0.2 https://example.com
--doh-cert-status--cert-status for DNS-over-HTTPS. 

Example:
curl --doh-cert-status --doh-url https://doh.server https://example.com 
--doh-insecure-k, --insecure for DoH.

Example:
curl --doh-insecure --doh-url https://doh.server https://example.com
--doh-url <URL>Specify a DoH server for hostname resolution. 

Example:
curl --doh-url https://doh.server https://example.com 
-D, --dump-header <filename>Specify a file for writing protocol headers. 

Example:
curl --dump-header store.txt https://example.com 
--egd-file <file>Provide a path for the EGD socket. 

Example:
curl --egd-file /path/here https://example.com 
--engine <name>Specify an OpenSSL crypto engine.

Example:
curl --engine flavor https://example.com  
--etag-compare <file>Request an ETag read from a file.

Example:
curl --etag-compare etag.txt https://example.com  
--etag-save <file>Save a HTTP ETag to a file. 

Example:
curl --etag-save etag.txt https://example.com 
--expect100-timeout <seconds>Maximum wait time for a 100-continue response. 

Example:
curl --expect100-timeout 2.5 -T file https://example.com 
--fail-earlyTell curl to fail and exit when it detects the first error in transfer. 

Example:
curl --fail-early https://example.com https://two.example 
--fail-with-bodyIf the server returns an error with code 400 or greater, curl saves the content and returns error 22.  

Example:
curl --fail-with-body https://example.com 
-f, --failIf the server returns an error, curl fails silently and returns error 22. 

Example:
curl --fail https://example.com 
--false-startUse false start on TLS handshake. 

Example:
curl --false-start https://example.com 
--form-string <name=string>Similar to -F, --form, but the value strings are processed literally. 

Example:
curl --form-string "data" https://example.com 
-F, --form <name=content>Emulate a form with a Submit button that has been pressed. The @ sign forces the content to be a file. The < sign extracts only the content part of the file.  

Example:
curl --form "name=curl" --form "file=@loadthis" https://example.com
--ftp-account <data>Specify the account data for the FTP server. 

Example:
curl --ftp-account "account_data" ftp://example.com/
--ftp-alternative-to-user <command>Specify the command to be sent if the username and password authentication fails. 

Example:
curl --ftp-alternative-to-user "U53r" ftp://example.com 
--ftp-create-dirsIf the specified directory does not exist, curl will attempt to create it.

Example:
curl --ftp-create-dirs -T file ftp://example.com/dirs/one/file 
--ftp-method <method>Specify a method to be used for obtaining files over FTP. Available methods are multicwd, nocwd, and singlecwd.  

Example:
curl --ftp-method multicwd ftp://example.com/dir1/dir2/file 
--ftp-pasvUse passive data connection mode. 

Example:
curl --ftp-pasv ftp://example.com/ 
-P, --ftp-port <address>Reverse the default roles for the FTP connection. 

Example:
curl -P eth0 ftp:/example.com 
--ftp-pretSend the PRET command before PASV/EPSV.

Example:
curl --ftp-pret ftp://example.com/ 
--ftp-skip-pasv-ipDo not use the IP address suggested by the server. curl will use the control connection IP. 

Example:
curl --ftp-skip-pasv-ip ftp://example.com/ 
--ftp-ssl-ccc-mode <active/passive>Set the Clear Command Channel (CCC) mode.

Example:
curl --ftp-ssl-ccc-mode active --ftp-ssl-ccc ftps://example.com/ 
--ftp-ssl-cccAfter the authentication is complete, the SSL/TLS layer is eliminated, allowing for unencrypted communication. 

Example:
curl --ftp-ssl-ccc ftps://example.com/ 
--ftp-ssl-controlUse SSL/TLS for logging in, stop the encryption when the data transfer starts.

Example:
curl --ftp-ssl-control ftp://example.com 
-G, --getUse HTTP GET request instead of POST. 

Example:
curl --get -d "tool=curl" -d "age=old" https://example.com
-g, --globoffDisable the URL globbing parser.

Example:
curl -g "https://example.com/{[]}}}}"  
--happy-eyeballs-timeout-ms <milliseconds>Use the Happy Eyeballs algorithm for connecting to dual-stack hosts. 

Example:
curl --happy-eyeballs-timeout-ms 500 https://example.com 
--haproxy-protocolUse HAProxy PROXY protocol v1 header. 

Example:
curl --haproxy-protocol https://example.com 
-I, --headObtain only headers.

Example:
curl -I https://example.com 
-H, --header <header/@file>Specify an additional header to be sent in the HTTP request. 

Example:
curl -H "X-First-Name: Joe" https://example.com 
-h, --help <category>See help for a specific category. all lists all the available options. 

Example:
curl --help all 
--hostpubmd5 <md5>Pass a 32-digit hexadecimal string. 

Example:
curl --hostpubmd5 e5c1c49020640a5ab0f2034854c321a8 sftp://example.com/ 
--hsts <file name>Enable HSTS. 

Example:
curl --hsts cache.txt https://example.com 
--http0.9Accept a HTTP version 0.9 response. 

Example:
curl --http0.9 https://example.com
-0, --http1.0Use HTTP version 1.0. 

Example:
curl --http1.0 https://example.com
--http1.1Use HTTP version 1.1.   

Example:
curl --http1.1 https://example.com 
--http2-prior-knowledgeUse HTTP version 2.0. Use this option if you know that the server supports this HTTP version. 

Example:
curl --http2-prior-knowledge https://example.com
--http2Attempt to use HTTP version 2.0. 

Example:
curl --http2 https://example.com
--http3Use HTTP version 3.0. This is an experimental option.   

Example:
curl --http3 https://example.com
--ignore-content-lengthIgnore the Content-Length header.

Example:
curl --ignore-content-length https://example.com 
-i, --includeSpecify that the output should include the HTTP response headers. 

Example:
curl -i https://example.com
-k, --insecureAllow curl to work with insecure connections. 

Example:
curl --insecure https://example.com 
--interface <name>Specify the interface for performing an action. 

Example:
curl --interface eth0 https://example.com 
-4, --ipv4Only resolve names to IPv4 addresses. 

Example:
curl --ipv4 https://example.com 
-6, --ipv6Only resolve names to IPv6 addresses.

Example:
curl --ipv6 https://example.com
-j, --junk-session-cookiesDiscard session cookies. 

Example:
curl --junk-session-cookies -b cookies.txt https://example.com 
--keepalive-time <seconds>Specify the idle time for the connection before it sends keepalive probes. 

Example:
curl --keepalive-time 30 https://example.com 
--key-type <type>Specify the type of the private key. Available types are PEM (default), DER, and ENG

Example:
curl --key-type ENG --key here https://example.com 
--key <key>Specify the file containing the private key. 

Example:
curl --cert certificate --key here https://example.com 
--krb <level>Enable and use Kerberos authentication. Available levels are clear, safe, confidential, and private (default). 

Example:
curl --krb clear ftp://example.com/ 
--libcurl <file>Obtain C source code for the specified command line operation. 

Example:
curl --libcurl client.c https://example.com 
--limit-rate <speed>Specify the maximum upload and download transfer rate. 

Example:
curl --limit-rate 100K https://example.com 
-l, --list-onlyForce a name-only view. 

Example:
curl --list-only ftp://example.com/dir/ 
--local-port <num/range>Specify the port numbers to be used for the connection. 

Example:
curl --local-port 1000-3000 https://example.com 
--location-trustedSimilar to -L, --location, but enables you to send name and password to all redirections.

Example:
curl --location-trusted -u user:pass https://example.com
-L, --locationAllow curl to follow any redirections. 

Example:
curl -L https://example.com 
--login-options <options>Specify the login options for email server authentication. 

Example:
curl --login-options 'AUTH=*' imap://example.com 
--mail-auth <address>Provide a single address as the identity. 

Example:
curl --mail-auth user@example.come -T mail smtp://example.com/ 
--mail-from <address>Provide a single "from" address.

Example:
curl --mail-from user@example.com -T mail smtp://example.com/ 
--mail-rcpt-allowfailsAllows curl to continue with SMTP conversation if one of the recipients fails. 

Example:
curl --mail-rcpt-allowfails --mail-rcpt dest@example.com smtp://example.com 
--mail-rcpt <address>Provide a single "to" address.  

Example:
curl --mail-rcpt user@example.net smtp://example.com 
-M, --manualRead the curl manual. 

Example:
curl --manual 
--max-filesize <bytes>Provide the maximum size of the file to be downloaded.  
Example:
curl --max-filesize 500K https://example.com 
--max-redirs <num>Specify the maximum number of redirections when --location is active. 

Example:
curl --max-redirs 3 --location https://example.com 
-m, --max-time <fractional seconds>Specify the maximum time for an operation. 

Example:
curl --max-time 5.52 https://example.com 
--metalinkSpecify a metalink resource. This option is disabled in the newest versions of curl. 

Example:
curl --metalink file https://example.com 
--negotiateEnable SPNEGO authentication. 

Example:
curl --negotiate -u : https://example.com
--netrc-file <filename>Like --n, --netrc, but allows you to specify the file to be used. 

Example:
curl --netrc-file netrc https://example.com 
--netrc-optionalLike --n, --netrc, but using netrc is optional. 

Example:
curl --netrc-optional https://example.com 
-n, --netrcSearch the netrc file for login information.

Example:
curl --netrc https://example.com 
-:, --nextUse the option to separate URL requests. 

Example:
curl -I https://example.com --next https://example.net/ 
--no-alpnDisable ALPN TLS extension. 

Example:
curl --no-alpn https://example.com 
-N, --no-bufferDisable output stream buffer. 

Example:
curl --no-buffer https://example.com 
--no-keepaliveDisable keepalive messages. 

Example:
curl --no-keepalive https://example.com 
--no-npnDisable NPN TLS extension. 

Example:
curl --no-npn https://example.com 
--no-progress-meterDisable the progress bar but display any other message. 

Example:
curl --no-progress-meter -o store https://example.com 
--no-sessionidDisable the caching of SSL session-ID. 

Example:
curl --no-sessionid https://example.com 
--noproxy <no-proxy-list>List the hosts which should not use a proxy. 

Example:
curl --noproxy "www.example" https://example.com 
--ntlm-wbLike --ntlm, but also hands authentication to ntlmauth.

Example:
curl --ntlm-wb -u user:password https://example.com  
--ntlmEnable NTLM authentication. 

Example:
curl --ntlm -u user:password https://example.com 
--oauth2-bearer <token>Provide a Bearer Token for OAUTH 2.0. 

Example:
curl --oauth2-bearer "mF_9.B5f-4.1JqM" https://example.com 
--output-dir <dir>Specify the output file directory.

Example:
curl --output-dir "tmp" -O https://example.com 
-o, --output <file>Store output in a file. The output is not shown in stdout. 

Example:
curl -o file https://example.com -o file2 https://example.net 
--parallel-immediatePrefer parallel connections to waiting for new connections or multiplexed streams. 

Example:
curl --parallel-immediate -Z https://example.com -o file1 https://example.com -o file2
--parallel-max <num>Specify the maximum number of parallel connections. 

Example:
curl --parallel-max 100 -Z https://example.com ftp://example.com/ 
-Z, --parallelPerform transfers in parallel.

Example:
curl --parallel https://example.com -o file1 https://example.com -o file2
--pass <phrase>Specify a private key passphrase. 

Example:
curl --pass secret --key file https://example.com 
--path-as-isPrevent curl from merging /./ and /../ sequences. 

Example:
curl --path-as-is https://example.com/../../etc/passwd
--pinnedpubkey <hashes>Specify a public key for curl to use. 

Example:
curl --pinnedpubkey keyfile https://example.com 
--post301Prevent curl from converting POST to GET requests after a 301 redirection. 

Example:
curl --post301 --location -d "data" https://example.com 
--post302Prevent curl from converting POST to GET requests after a 302 redirection.  

curl --post302 --location -d "data" https://example.com 
--post303Prevent curl from converting POST to GET requests after a 303 redirection.  

Example:
curl --post303 --location -d "data" https://example.com 
--preproxy [protocol://]host[:port]Use the SOCKS proxy as a pre-proxy. 

Example:
curl --preproxy socks5://proxy.example -x http://http.example https://example.com 
-#, --progress-barUse the simple progress bar.

Example:
curl -# -O https://example.com 
--proto-default <protocol>Specify which protocol curl should use for URLs without a scheme name. 

Example:
curl --proto-default https ftp.example.com 
--proto-redir <protocols>Specify which protocols curl should use on redirection. 

Example:
curl --proto-redir =http,https https://example.com 
--proto <protocols>Specify which protocols curl should use for transfers.  

Example:
curl --proto =http,https,sftp https://example.com 
--proxy-anyauthCurl should choose an appropriate authentication method. 

Example:
curl --proxy-anyauth --proxy-user user:passwd -x proxy https://example.com
--proxy-basicUse HTTP Basic for communication with a proxy. 

Example:
curl --proxy-basic --proxy-user user:passwd -x proxy https://example.com 
--proxy-cacert <file>--cacert for HTTPS proxies. 

Example:
curl --proxy-cacert CA-file.txt -x https://proxy https://example.com 
--proxy-capath <dir>--capath for HTTPS proxies. 

Example:
curl --proxy-capath /local/directory -x https://proxy https://example.com
--proxy-cert-type <type>--cert-type for HTTPS proxies. 

Example:
curl --proxy-cert-type PEM --proxy-cert file -x https://proxy https://example.com
--proxy-cert <cert[:passwd]>-E, --cert for HTTPS proxies. 

Example:
curl --proxy-cert file -x https://proxy https://example.com 
--proxy-ciphers <list>--ciphers for HTTPS proxies. 

curl --proxy-ciphers ECDHE-ECDSA-AES256-CCM8 -x https://proxy https://example.com 
--proxy-crlfile <file>--crlfile for HTTPS proxies. 

Example:
curl --proxy-crlfile rejects.txt -x https://proxy https://example.com
--proxy-digestUse HTTP Digest authentication with a proxy. 

Example:
curl --proxy-digest --proxy-user user:passwd -x proxy https://example.com 
--proxy-header <header/@file>-H, --header for proxy communication. 

Example:
curl --proxy-header "Host:" -x http://proxy https://example.com 
--proxy-insecure-k, --insecure for HTTPS proxies. 

Example:
curl --proxy-insecure -x https://proxy https://example.com 
--proxy-key-type <type>--key-type for HTTPS proxies. 

Example:
curl --proxy-key-type DER --proxy-key here -x https://proxy https://example.com 
--proxy-key <key>--key for HTTPS proxies. 

Example:
curl --proxy-key here -x https://proxy https://example.com 
--proxy-negotiate--negotiate for proxy communication.

Example:
curl --proxy-negotiate --proxy-user user:passwd -x proxy https://example.com
--proxy-ntlmUse HTTP NTLM authentication with a proxy.

Example:
curl --proxy-ntlm --proxy-user user:passwd -x http://proxy https://example.com
--proxy-pass <phrase>--pass for HTTPS proxies. 

Example:
curl --proxy-pass secret --proxy-key here -x https://proxy https://example.com 
--proxy-pinnedpubkey <hashes>Specify the public key for proxy verification. 

Example:
curl --proxy-pinnedpubkey keyfile https://example.com 
--proxy-service-name <name>Specify the service name for proxy communciation. 

Example:
curl --proxy-service-name "shrubbery" -x proxy https://example.com 
--proxy-ssl-allow-beast--ssl-allow-beast for HTTPS proxies. 

Example:
curl --proxy-ssl-allow-beast -x https://proxy https://example.com 
--proxy-ssl-auto-client-cert--ssl-auto-client-cert for HTTPS proxies. 

Example:
curl --proxy-ssl-auto-client-cert -x https://proxy https://example.com 
--proxy-tls13-ciphers <ciphersuite list>Specifies the list of cipher suites to use in negotiating TLS 1.3 for proxies. 

Example:
curl --proxy-tls13-ciphers TLS_AES_128_GCM_SHA256 -x proxy https://example.com
--proxy-tlsauthtype <type>--tlsauthtype for HTTPS proxies. 

Example:
curl --proxy-tlsauthtype SRP -x https://proxy https://example.com 
--proxy-tlspassword <string>--tlspassword for HTTPS proxies.

Example:
curl --proxy-tlspassword passwd -x https://proxy https://example.com 
--proxy-tlsuser <name>--tlsuser for HTTPS proxies. 

Example:
curl --proxy-tlsuser smith -x https://proxy https://example.com 
--proxy-tlsv1-1, --tlsv1 for HTTPS proxies. 

Example:
curl --proxy-tlsv1 -x https://proxy https://example.com 
-U, --proxy-user <user:password>Specify the username and password for authenticating with a proxy.

Example:
curl --proxy-user name:pwd -x proxy https://example.com 
-x, --proxy [protocol://]host[:port]Specify a proxy to use.

Example:
curl --proxy http://proxy.example https://example.com 
--proxy1.0 <host[:port]>Specify a HTTP 1.0 proxy to use. 

Example:
curl --proxy1.0 -x http://proxy https://example.com 
-p, --proxytunnelCreate a proxy tunnel.

Example:
curl --proxytunnel -x http://proxy https://example.com 
--pubkey <key>Provide a file containing a public key. 

Example:
curl --pubkey file.pub sftp://example.com/ 
-Q, --quote <command>Send a command to a FTP or SFTP server, to be executed before the transfer. 

Example:
curl --quote "rm file" ftp://example.com/foo 
--random-file <file>Specify a file containing random data. This file will be used for seeding the random engine. 

Example:
curl --random-file rubbish https://example.com 
-r, --range <range>Obtain a range of bytes. 

Example:
curl --range 40-80 https://example.com 
--rawDisable HTTP content decoding and obtain raw data. 

Example:
curl --raw https://example.com 
-e, --referer <URL>Send Referrer Page information. 

Example:
curl --referer "https://test.example" https://example.com 
-J, --remote-header-nameUse header name specified by the server instead of obtaining it from the URL.

Example:
curl -OJ https://example.com/file 
--remote-name-allApply the -O, --remote-name option to all the URLs.

Example:
curl --remote-name-all ftp://example.com/file1 ftp://example.com/file2 
-O, --remote-nameSpecify that the local file should have the name of the remote file that was downloaded.

Example:
curl -O https://example.com/filename 
-R, --remote-timeSpecify that the local file should have the timestamp of the remote file that was downloaded.

Example:
curl --remote-time -o foo https://example.com 
--request-target <path>Specify an alternative target path.

Example:
curl --request-target "*" -X OPTIONS https://example.com 
-X, --request <command>Specify a request method for communication with the server.

Example:
curl -X "DELETE" https://example.com 
--resolve <[+]host:port:addr[,addr]...>Specify a custom address for a host/port. 

Example:
curl --resolve example.com:443:127.0.0.1 https://example.com 
--retry-all-errorsForce retrying on all errors.

Example:
curl --retry-all-errors https://example.com 
--retry-connrefusedAdd ECONNREFUSED to the list of errors that are eligible for --retry

Example:
curl --retry-connrefused --retry https://example.com 
--retry-delay <seconds>Specify the amount of time between retries. 

Example:
curl --retry-delay 5 --retry https://example.com 
--retry-max-time <seconds>Specify the maximum amount of time for --retry attempts. 

Example:
curl --retry-max-time 30 --retry 10 https://example.com 
--retry <num>Specify the number of retries after curl encounters and error. 

Example:
curl --retry 7 https://example.com
--sasl-authzid <identity>Specify an additional authentication identity for SASL PLAIN authentication. 

Example:
curl --sasl-authzid zid imap://example.com/ 
--sasl-irEnable initial response during SASL authentication.

Example:
curl --sasl-ir imap://example.com/ 
--service-name <name>Specify the SPNEGO service name. 

Example:
curl --service-name sockd/server https://example.com 
-S, --show-errorShow an error message event with the -s, --silent option enabled. 

Example:
curl --show-error --silent https://example.com 
-s, --silentTurn on the silent mode. This option mutes curl.

Example:
curl -s https://example.com 
--socks4 <host[:port]>Specify a SOCKS4 proxy.

Example:
curl --socks4 hostname:4096 https://example.com 
--socks4a <host[:port]>Specify a SOCKS4a proxy. 

Example:
curl --socks4a hostname:4096 https://example.com 
--socks5-basicUse the basic authentication method (username/password) with a SOCKS5 proxy. 

Example:
curl --socks5-basic --socks5 hostname:4096 https://example.com 
--socks5-gssapi-necAllow protection mode negotiation to be unprotected.

Example:
curl --socks5-gssapi-nec --socks5 hostname:4096 https://example.com 
--socks5-gssapi-service <name>Change the name of a socks server.

Example:
curl --socks5-gssapi-service sockd --socks5 hostname:4096 https://example.com 
--socks5-gssapiUse GSS-API authentication with a SOCKS5 proxy. 

Example:
curl --socks5-gssapi --socks5 hostname:4096 https://example.com 
--socks5-hostname <host[:port]>Specify the SOCKS5 proxy to use. 

Example:
curl --socks5-hostname proxy.example:7000 https://example.com 
--socks5 <host[:port]>Specify the SOCKS5 proxy to use. The hostname is resolved locally. 

Example:
curl --socks5 proxy.example:7000 https://example.com 
-Y, --speed-limit <speed>Set the lower limit for the download speed.

Example:
curl --speed-limit 300 --speed-time 10 https://example.com 
-y, --speed-time <seconds>Set the time period for the speed limit measurement. 

Example:
curl --speed-limit 300 --speed-time 10 https://example.com 
--ssl-allow-beastTell curl to ignore the BEAST security flaw in the SSL3 and TLS1.0 protocols. 

Example:
curl --ssl-allow-beast https://example.com 
--ssl-auto-client-certObtain and use a client certificate automatically. 

Example:
curl --ssl-auto-client-cert https://example.com 
--ssl-no-revokeDo not check for certificate revocation. 

Example:
curl --ssl-no-revoke https://example.com 
--ssl-reqdRequire SSL/TLS. 

Example:
curl --ssl-reqd ftp://example.com 
--ssl-revoke-best-effortIgnore certificate revocation checks if they failed because of missing distribution points.

Example:
curl --ssl-revoke-best-effort https://example.com 
--sslAttempt to use SSL. 

Example:
curl --ssl pop3://example.com/ 
-2, --sslv2Use SSLv2. Newer curl versions ignore this request due to security concerns with SSLv2.

Example:
curl --sslv2 https://example.com 
-3, --sslv3Use SSLv3. Newer curl versions ignore this request due to security concerns with SSLv3.  

Example:
curl --sslv3 https://example.com 
--stderr <file>Output stderr to a file. The - symbol tells curl to output stderr to stdout. 

Example:
curl --stderr output.txt https://example.com 
--styled-outputEnable bold fonts for HTTP header terminal output. 

curl --styled-output -I https://example.com 
--suppress-connect-headersPrevent curl from outputting CONNECT headers. 

Example:
curl --suppress-connect-headers --include -x proxy https://example.com 
--tcp-fastopenEnable TCP Fast Open.

Example:
curl --tcp-fastopen https://example.com
--tcp-nodelayEnable TCP_NODELAY. 

Example:
curl --tcp-nodelay https://example.com 
-t, --telnet-option <opt=val>Pass the TTYPE, XDISPLOC, and NEW_ENV options to the telnet protocol. 

Example:
curl -t TTYPE=vt100 telnet://example.com/ 
--tftp-blksize <value>Set the value of TFTP BLKSIZE. Must be a value larger than 512. 

Example:
curl --tftp-blksize 1024 tftp://example.com/file 
--tftp-no-optionsPrevents curl from sending requests for TFTP options.

Example:
curl --tftp-no-options tftp://192.168.0.1/ 
-z, --time-cond <time>Request a document that was modified after a certain date and time. For documents modified before the time, prefix the date expression with a dash.
 
Example:
curl -z "Wed 01 Sep 2021 12:18:00" https://example.com 
--tls-max <VERSION>Specify the newest TLS version that is supported.

Example:
curl --tls-max 1.2 https://example.com 
--tls13-ciphers <ciphersuite list>Specifies the list of cipher suites to use in negotiating TLS 1.3  

Example:
curl --tls13-ciphers TLS_AES_128_GCM_SHA256 https://example.com 
--tlsauthtype <type>Specify the TLS authentication type.

Example:
curl --tlsauthtype SRP https://example.com 
--tlspassword <string>Specify the TLS password. 

Example:
curl --tlspassword pwd --tlsuser user https://example.com 
--tlsuser <name>Specify the TLS username. 

Example:
curl --tlspassword pwd --tlsuser user https://example.com 
--tlsv1.0Tell curl to use TLS1.0 or newer. 

Example:
curl --tlsv1.0 https://example.com 
--tlsv1.1Tell curl to use TLS1.1 or newer.  

Example:
curl --tlsv1.1 https://example.com 
--tlsv1.2Tell curl to use TLS1.2 or newer.  

Example:
curl --tlsv1.2 https://example.com 
--tlsv1.3Tell curl to use TLS1.3 or newer.  

Example:
curl --tlsv1.3 https://example.com 
-1, --tlsv1Specify that curl should use at least 1.x version of TLS.

Example:
curl --tlsv1 https://example.com 
--tr-encodingAsk for a compressed Transfer-Encoding response.

Example:
curl --tr-encoding https://example.com 
--trace-ascii <file>Enable a full trace dump to a file. Eliminates the hex part and shows only ASCII.

Example:
curl --trace-ascii log.txt https://example.com 
--trace-timeRequire a time stamp on each trace or verbose line. 

Example:
curl --trace-time --trace-ascii output https://example.com 
--trace <file>Enable a full trace dump to a file.  

Example:
curl --trace log.txt https://example.com 
--unix-socket <path>Specify a Unix socket path. 

Example:
curl --unix-socket socket-path https://example.com 
-T, --upload-file <file>Upload a file to the URL. 

Example:
curl -T "img[1-1000].png" ftp://ftp.example.com/ 
--url <url>Provide a URL to be fetched. 

Example:
curl --url https://example.com 
-B, --use-asciiEnable ASCII transfer. 

Example:
curl -B ftp://example.com/README 
-A, --user-agent <name>Specify the user agent name. 

Example:
curl -A "Agent 007" https://example.com 
-u, --user <user:password>Provide the username and password for authentication. 

Example:
curl -u user:secret https://example.com 
-v, --verboseTell curl to be verbose. 

Example:
curl --verbose https://example.com 
-V, --versionSee the installed versions of curl and libcurl.

Example:
curl --version 
-w, --write-out <format>Tell curl to show information about the completed transfer on stdout. 

Example:
curl -w '%{http_code}\n' https://example.com 
--xattrStore file metadata in file attributes.

Example:
curl --xattr -o storage https://example.com  

For comprehensive descriptions of the options, execute the curl --manual command in the terminal.

Conclusion

After reading this tutorial, you should know how to use the curl command along with its numerous options. To find out more about what curl can do, read How to Set or Change User Agent with curl.

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Marko Aleksic
Marko Aleksić is a Technical Writer at phoenixNAP. His innate curiosity regarding all things IT, combined with over a decade long background in writing, teaching and working in IT-related fields, led him to technical writing, where he has an opportunity to employ his skills and make technology less daunting to everyone.
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