Introduction to cURL

The cURL package contains an utility and a library used for transferring files with URL syntax to any of the following protocols: DICT, FILE, FTP, FTPS, GOPHER, GOPHERS, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, MQTT, POP3, POP3S, RTSP, SMB, SMBS, SMTP, SMPTS, TELNET, and TFTP. Its ability to both download and upload files can be incorporated into other programs to support functions like streaming media.

This package is known to build and work properly using an LFS 12.1 platform.

Package Information

  • Download (HTTP):

  • Download MD5 sum: 8f28f7e08c91cc679a45fccf66184fbc

  • Download size: 2.5 MB

  • Estimated disk space required: 42 MB (add 18 MB for tests)

  • Estimated build time: 0.2 SBU (with parallelism=4; add 4.1 SBU for tests (without valgrind, add 36 SBU with valgrind))

cURL Dependencies




While there is an option to build the package without libpsl, both the upstream developers and the BLFS editors alike highly recommend not disabling support for libpsl due to severe security implications.

Recommended at runtime


Brotli-1.1.0, c-ares-1.26.0, GnuTLS-3.8.3, libidn2-2.3.7, libssh2-1.11.0, MIT Kerberos V5-1.21.2, nghttp2-1.59.0, OpenLDAP-2.6.7, Samba-4.19.5 (runtime, for NTLM authentication), gsasl, impacket, libmetalink, librtmp, ngtcp2, quiche, and SPNEGO

Optional if Running the Test Suite

Apache-2.4.58 and stunnel-5.72 (for the HTTPS and FTPS tests), OpenSSH-9.6p1, and Valgrind-3.22.0 (this will slow the tests down and may cause failures.)

Installation of cURL

Install cURL by running the following commands:

./configure --prefix=/usr                           \
            --disable-static                        \
            --with-openssl                          \
            --enable-threaded-resolver              \
            --with-ca-path=/etc/ssl/certs &&

To run the test suite, issue: make test. Some tests are flaky, so if some tests have failed it's possible to run a test again with: (cd tests; ./ <test ID>) (the ID of failed tests are shown in the These test cases failed: message). If you run the tests after the package has been installed, some tests may fail because the man pages were deleted by the 'find' command in the installation instructions below.

Now, as the root user:

make install &&

rm -rf docs/examples/.deps &&

find docs \( -name Makefile\* -o  \
             -name \*.1       -o  \
             -name \*.3       -o  \
             -name CMakeLists.txt \) -delete &&

cp -v -R docs -T /usr/share/doc/curl-8.6.0

To run some simple verification tests on the newly installed curl, issue the following commands: curl --trace-ascii debugdump.txt and curl --trace-ascii d.txt --trace-time Inspect the locally created trace files debugdump.txt and d.txt, which contains version information, downloaded files information, etc. One file has the time for each action logged.

Command Explanations

--disable-static: This switch prevents installation of static versions of the libraries.

--enable-threaded-resolver: This switch enables cURL's builtin threaded DNS resolver.

--with-ca-path=/etc/ssl/certs: This switch sets the location of the BLFS Certificate Authority store.

--with-openssl: This parameter chooses OpenSSL as SSL/TLS implementation. This seems mandatory now.

--with-gssapi: This parameter adds Kerberos 5 support to libcurl.

--without-ssl --with-gnutls: Use this switch to build with GnuTLS support instead of OpenSSL for SSL/TLS.

--with-ca-bundle=/etc/pki/tls/certs/ca-bundle.crt: Use this switch instead of --with-ca-path if building with GnuTLS support instead of OpenSSL for SSL/TLS.

--with-libssh2: This parameter adds SSH support to cURL. This is disabled by default.

--enable-ares: This parameter adds support for DNS resolution through the c-ares library. It overrides --enable-threaded-resolver and is not widely tested by the editors.

find docs ... -exec rm {} \;: This command removes Makefiles and man files from the documentation directory that would otherwise be installed by the commands that follow.


Installed Programs: curl and curl-config
Installed Library:
Installed Directories: /usr/include/curl and /usr/share/doc/curl-8.6.0

Short Descriptions


is a command line tool for transferring files with URL syntax


prints information about the last compile, like libraries linked to and prefix setting

provides the API functions required by curl and other programs