DOKK / manpages / debian 10 / ca-certificates / update-ca-certificates.8.en

update-ca-certificates - update /etc/ssl/certs and ca-certificates.crt

update-ca-certificates [options]

This manual page documents briefly the update-ca-certificates command.

update-ca-certificates is a program that updates the directory /etc/ssl/certs to hold SSL certificates and generates ca-certificates.crt, a concatenated single-file list of certificates.

It reads the file /etc/ca-certificates.conf. Each line gives a pathname of a CA certificate under /usr/share/ca-certificates that should be trusted. Lines that begin with "#" are comment lines and thus ignored. Lines that begin with "!" are deselected, causing the deactivation of the CA certificate in question. Certificates must have a .crt extension in order to be included by update-ca-certificates.

Furthermore all certificates with a .crt extension found below /usr/local/share/ca-certificates are also included as implicitly trusted.

Before terminating, update-ca-certificates invokes run-parts on /etc/ca-certificates/update.d and calls each hook with a list of certificates: those added are prefixed with a +, those removed are prefixed with a -.

A summary of options is included below.

Show summary of options.
Be verbose. Output openssl rehash.
Fresh updates. Remove symlinks in /etc/ssl/certs directory.

A configuration file.
A single-file version of CA certificates. This holds all CA certificates that you activated in /etc/ca-certificates.conf.
Directory of CA certificates.
Directory of local CA certificates (with .crt extension).


This manual page was written by Fumitoshi UKAI <>, for the Debian project (but may be used by others).

20 April 2003