curl/docs/cmdline-opts/page-header

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.TH curl 1 "16 Dec 2016" "Curl 7.52.0" "Curl Manual"
.SH NAME
curl \- transfer a URL
.SH SYNOPSIS
.B curl [options / URLs]
.SH DESCRIPTION
.B curl
is a tool to transfer data from or to a server, using one of the supported
protocols (DICT, FILE, FTP, FTPS, GOPHER, HTTP, HTTPS, IMAP, IMAPS, LDAP,
LDAPS, MQTT, POP3, POP3S, RTMP, RTMPS, RTSP, SCP, SFTP, SMB, SMBS, SMTP,
SMTPS, TELNET and TFTP). The command is designed to work without user
interaction.

curl offers a busload of useful tricks like proxy support, user
authentication, FTP upload, HTTP post, SSL connections, cookies, file transfer
resume, Metalink, and more. As you will see below, the number of features will
make your head spin!

curl is powered by libcurl for all transfer-related features. See
\fIlibcurl(3)\fP for details.
.SH URL
The URL syntax is protocol-dependent. You'll find a detailed description in
RFC 3986.

You can specify multiple URLs or parts of URLs by writing part sets within
braces and quoting the URL as in:

  "http://site.{one,two,three}.com"

or you can get sequences of alphanumeric series by using [] as in:

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

  "ftp://ftp.example.com/file[001-100].txt"    (with leading zeros)

  "ftp://ftp.example.com/file[a-z].txt"

Nested sequences are not supported, but you can use several ones next to each
other:

  "http://example.com/archive[1996-1999]/vol[1-4]/part{a,b,c}.html"

You can specify any amount of URLs on the command line. They will be fetched
in a sequential manner in the specified order. You can specify command line
options and URLs mixed and in any order on the command line.

You can specify a step counter for the ranges to get every Nth number or
letter:

  "http://example.com/file[1-100:10].txt"

  "http://example.com/file[a-z:2].txt"

When using [] or {} sequences when invoked from a command line prompt, you
probably have to put the full URL within double quotes to avoid the shell from
interfering with it. This also goes for other characters treated special, like
for example '&', '?' and '*'.

Provide the IPv6 zone index in the URL with an escaped percentage sign and the
interface name. Like in

  "http://[fe80::3%25eth0]/"

If you specify URL without protocol:// prefix, curl will attempt to guess what
protocol you might want. It will then default to HTTP but try other protocols
based on often-used host name prefixes. For example, for host names starting
with "ftp." curl will assume you want to speak FTP.

curl will do its best to use what you pass to it as a URL. It is not trying to
validate it as a syntactically correct URL by any means but is instead
\fBvery\fP liberal with what it accepts.

curl will attempt to re-use connections for multiple file transfers, so that
getting many files from the same server will not do multiple connects /
handshakes. This improves speed. Of course this is only done on files
specified on a single command line and cannot be used between separate curl
invokes.
.SH OUTPUT
If not told otherwise, curl writes the received data to stdout. It can be
instructed to instead save that data into a local file, using the --output or
--remote-name options. If curl is given multiple URLs to transfer on the
command line, it similarly needs multiple options for where to save them.

curl does not parse or otherwise "understand" the content it gets or writes as
output. It does no encoding or decoding, unless explictly asked so with
dedicated command line options.
.SH PROTOCOLS
curl supports numerous protocols, or put in URL terms: schemes. Your
particular build may not support them all.
.IP DICT
Lets you lookup words using online dictionaries.
.IP FILE
Read or write local files. curl does not support accessing file:// URL
remotely, but when running on Microsft Windows using the native UNC approach
will work.
.IP FTP(S)
curl supports the File Transfer Protocol with a lot of tweaks and levers. With
or without using TLS.
.IP GOPHER
Retrieve files.
.IP HTTP(S)
curl supports HTTP with numerous options and variations. It can speak HTTP
version 0.9, 1.0, 1.1, 2 and 3 depending on build options and the correct
command line options.
.IP IMAP(S)
Using the mail reading protocol, curl can "download" emails for you. With or
without using TLS.
.IP LDAP(S)
curl can do directory lookups for you, with or without TLS.
.IP MQTT
curl supports MQTT version 3. Downloading over MQTT equals "subscribe" to a
topic while uploading/posting equals "publish" on a topic. MQTT support is
experimental and TLS based MQTT is not supported (yet).
.IP POP3(S)
Downloading from a pop3 server means getting a mail. With or without using
TLS.
.IP RTMP(S)
The Realtime Messaging Protocol is primarily used to server streaming media
and curl can download it.
.IP RTSP
curl supports RTSP 1.0 downloads.
.IP SCP
curl supports SSH version 2 scp transfers.
.IP SFTP
curl supports SFTP (draft 5) done over SSH version 2.
.IP SMB(S)
curl supports SMB version 1 for upload and download.
.IP SMTP(S)
Uploading contents to an SMTP server means sending an email. With or without
TLS.
.IP TELNET
Telling curl to fetch a telnet URL starts an interactive session where it
sends what it reads on stdin and outputs what the server sends it.
.IP TFTP
curl can do TFTP downloads and uploads.
.SH "PROGRESS METER"
curl normally displays a progress meter during operations, indicating the
amount of transferred data, transfer speeds and estimated time left, etc. The
progress meter displays number of bytes and the speeds are in bytes per
second. The suffixes (k, M, G, T, P) are 1024 based. For example 1k is 1024
bytes. 1M is 1048576 bytes.

curl displays this data to the terminal by default, so if you invoke curl to
do an operation and it is about to write data to the terminal, it
\fIdisables\fP the progress meter as otherwise it would mess up the output
mixing progress meter and response data.

If you want a progress meter for HTTP POST or PUT requests, you need to
redirect the response output to a file, using shell redirect (>), --output or
similar.

It is not the same case for FTP upload as that operation does not spit out
any response data to the terminal.

If you prefer a progress "bar" instead of the regular meter, --progress-bar is
your friend. You can also disable the progress meter completely with the
--silent option.
.SH OPTIONS
Options start with one or two dashes. Many of the options require an
additional value next to them.

The short "single-dash" form of the options, -d for example, may be used with
or without a space between it and its value, although a space is a recommended
separator. The long "double-dash" form, --data for example, requires a space
between it and its value.

Short version options that don't need any additional values can be used
immediately next to each other, like for example you can specify all the
options -O, -L and -v at once as -OLv.

In general, all boolean options are enabled with --\fBoption\fP and yet again
disabled with --\fBno-\fPoption. That is, you use the exact same option name
but prefix it with "no-". However, in this list we mostly only list and show
the --option version of them. (This concept with --no options was added in
7.19.0. Previously most options were toggled on/off on repeated use of the
same command line option.)